Robustness engine actions with stats and log (#685)

* Robustness engine actions with stats and logging - Add actions to robustness engine - Actions wrap other functional behavior and serve as a common interface for collecting stats - Add stats for the engine, both per run and cumulative over time - Add a log for actions that the engine has executed - Add recovery logic to re-sync snapshot metadata after a possible failed engine run (e.g. if metadata wasn't properly persisted). Current built-in actions: - snapshot root directory - restore random snapshot ID into a target restore path - delete a random snapshot ID - run GC - write random files to the local data directory - delete a random subdirectory under the local data directory - delete files in a directory - restore a snapshot ID into the local data directory Actions are executed according to a set of options, which dictate the relative probabilities of picking a given action, along with ranges for action-specific parameters that can be randomized.
2026-05-14 01:37:07 -04:00 · 2020-11-17 01:07:04 -08:00
parent ade7975212
commit 71dcbcf2e3
19 changed files with 1903 additions and 194 deletions
--- a/11
+++ b/11
@@ -205,9 +205,16 @@ endurance-tests: export KOPIA_EXE ?= $(KOPIA_INTEGRATION_EXE)
 endurance-tests: build-integration-test-binary $(gotestsum)
 	 $(GO_TEST) $(TEST_FLAGS) -count=1 -parallel $(PARALLEL) -timeout 3600s github.com/kopia/kopia/tests/endurance_test

-robustness-tool-tests: $(gotestsum)
+robustness-tests: export KOPIA_EXE ?= $(KOPIA_INTEGRATION_EXE)
+robustness-tests: build-integration-test-binary $(gotestsum)
 	FIO_DOCKER_IMAGE=$(FIO_DOCKER_TAG) \
-	$(GO_TEST) $(TEST_FLAGS) -count=1 -timeout 90s github.com/kopia/kopia/tests/tools/...
+	$(GO_TEST) -count=1 github.com/kopia/kopia/tests/robustness/robustness_test $(TEST_FLAGS)
+
+robustness-tool-tests: export KOPIA_EXE ?= $(KOPIA_INTEGRATION_EXE)
+robustness-tool-tests: build-integration-test-binary $(gotestsum)
+	KOPIA_EXE=$(KOPIA_INTEGRATION_EXE) \
+	FIO_DOCKER_IMAGE=$(FIO_DOCKER_TAG) \
+	$(GO_TEST) -count=1 github.com/kopia/kopia/tests/tools/... github.com/kopia/kopia/tests/robustness/engine/... $(TEST_FLAGS)

 stress-test: $(gotestsum)
 	KOPIA_LONG_STRESS_TEST=1 $(GO_TEST) -count=1 -timeout 200s github.com/kopia/kopia/tests/stress_test
--- a/tests/robustness/checker/checker.go
+++ b/tests/robustness/checker/checker.go
@@ -10,6 +10,7 @@
 	"io/ioutil"
 	"log"
 	"os"
+	"strconv"
 	"time"

 	"github.com/pkg/errors"
@@ -19,6 +20,11 @@
 	"github.com/kopia/kopia/tests/robustness/snapmeta"
 )

+const (
+	deleteLimitEnvKey  = "LIVE_SNAP_DELETE_LIMIT"
+	defaultDeleteLimit = 10
+)
+
 // Checker is an object that can take snapshots and restore them, performing
 // a validation for data consistency.
 type Checker struct {
@@ -26,21 +32,33 @@ type Checker struct {
 	snapshotIssuer        snap.Snapshotter
 	snapshotMetadataStore snapmeta.Store
 	validator             Comparer
+	RecoveryMode          bool
+	DeleteLimit           int
 }

 // NewChecker instantiates a new Checker, returning its pointer. A temporary
 // directory is created to mount restored data.
-func NewChecker(snapIssuer snap.Snapshotter, snapmetaStore snapmeta.Store, validator Comparer) (*Checker, error) {
-	restoreDir, err := ioutil.TempDir("", "restore-data-")
+func NewChecker(snapIssuer snap.Snapshotter, snapmetaStore snapmeta.Store, validator Comparer, restoreDir string) (*Checker, error) {
+	restoreDir, err := ioutil.TempDir(restoreDir, "restore-data-")
 	if err != nil {
 		return nil, err
 	}

+	delLimitStr := os.Getenv(deleteLimitEnvKey)
+
+	delLimit, err := strconv.Atoi(delLimitStr)
+	if err != nil {
+		log.Printf("using default delete limit %d", defaultDeleteLimit)
+		delLimit = defaultDeleteLimit
+	}
+
 	return &Checker{
 		RestoreDir:            restoreDir,
 		snapshotIssuer:        snapIssuer,
 		snapshotMetadataStore: snapmetaStore,
 		validator:             validator,
+		RecoveryMode:          false,
+		DeleteLimit:           delLimit,
 	}, nil
 }

@@ -53,7 +71,7 @@ func (chk *Checker) Cleanup() {

 // GetSnapIDs gets the list of snapshot IDs being tracked by the checker's snapshot store.
 func (chk *Checker) GetSnapIDs() []string {
-	return chk.snapshotMetadataStore.GetKeys()
+	return chk.snapshotMetadataStore.GetKeys(allSnapshotsIdxName)
 }

 // SnapshotMetadata holds metadata associated with a given snapshot.
@@ -73,18 +91,7 @@ func (chk *Checker) GetSnapshotMetadata(snapID string) (*SnapshotMetadata, error
 // GetLiveSnapIDs gets the list of snapshot IDs being tracked by the checker's snapshot store
 // that do not have a deletion time associated with them.
 func (chk *Checker) GetLiveSnapIDs() []string {
-	snapIDs := chk.GetSnapIDs()
-
-	var ret []string
-
-	for _, snapID := range snapIDs {
-		deleted, err := chk.IsSnapshotIDDeleted(snapID)
-		if err == nil && !deleted {
-			ret = append(ret, snapID)
-		}
-	}
-
-	return ret
+	return chk.snapshotMetadataStore.GetKeys(liveSnapshotsIdxName)
 }

 // IsSnapshotIDDeleted reports whether the metadata associated with the provided snapshot ID
@@ -125,14 +132,44 @@ func (chk *Checker) VerifySnapshotMetadata() error {

 	for _, metaSnapID := range liveSnapsInMetadata {
 		if _, ok := liveMap[metaSnapID]; !ok {
-			log.Printf("Metadata present for snapID %v but not found in known metadata", metaSnapID)
-			errCount++
+			log.Printf("Metadata present for snapID %v but not found in list of repo snapshots", metaSnapID)
+
+			if chk.RecoveryMode {
+				chk.snapshotMetadataStore.Delete(metaSnapID)
+				chk.snapshotMetadataStore.RemoveFromIndex(metaSnapID, liveSnapshotsIdxName)
+			} else {
+				errCount++
+			}
 		}
 	}

+	var liveSnapsDeleted int
+
 	for _, liveSnapID := range liveSnapsInRepo {
-		if _, ok := metadataMap[liveSnapID]; !ok {
-			log.Printf("Live snapshot present for snapID %v but not found in known metadata", liveSnapID)
+		if _, ok := metadataMap[liveSnapID]; ok {
+			// Found live snapshot ID in the metadata. No recovery handling needed.
+			continue
+		}
+
+		log.Printf("Live snapshot present for snapID %v but not found in known metadata", liveSnapID)
+
+		if chk.RecoveryMode {
+			if liveSnapsDeleted >= chk.DeleteLimit {
+				log.Printf("delete limit (%v) reached", chk.DeleteLimit)
+				errCount++
+			}
+
+			// Might as well delete the snapshot since we don't have metadata for it
+			log.Printf("Deleting snapshot ID %s", liveSnapID)
+
+			err = chk.snapshotIssuer.DeleteSnapshot(liveSnapID)
+			if err != nil {
+				log.Printf("error deleting snapshot: %s", err)
+				errCount++
+			}
+
+			liveSnapsDeleted++
+		} else {
 			errCount++
 		}
 	}
@@ -173,6 +210,9 @@ func (chk *Checker) TakeSnapshot(ctx context.Context, sourceDir string) (snapID
 		return snapID, err
 	}

+	chk.snapshotMetadataStore.AddToIndex(snapID, allSnapshotsIdxName)
+	chk.snapshotMetadataStore.AddToIndex(snapID, liveSnapshotsIdxName)
+
 	return snapID, nil
 }

@@ -211,6 +251,22 @@ func (chk *Checker) RestoreVerifySnapshot(ctx context.Context, snapID, destPath
 		return err
 	}

+	if ssMeta == nil && chk.RecoveryMode {
+		var b []byte
+
+		b, err = chk.validator.Gather(ctx, destPath)
+		if err != nil {
+			return err
+		}
+
+		ssMeta = &SnapshotMetadata{
+			SnapID:         snapID,
+			ValidationData: b,
+		}
+
+		return chk.saveSnapshotMetadata(ssMeta)
+	}
+
 	err = chk.validator.Compare(ctx, destPath, ssMeta.ValidationData, reportOut)
 	if err != nil {
 		return err
@@ -219,6 +275,12 @@ func (chk *Checker) RestoreVerifySnapshot(ctx context.Context, snapID, destPath
 	return nil
 }

+const (
+	deletedSnapshotsIdxName = "deleted-snapshots-idx"
+	liveSnapshotsIdxName    = "live-snapshots-idx"
+	allSnapshotsIdxName     = "all-snapshots-idx"
+)
+
 // DeleteSnapshot performs the Snapshotter's DeleteSnapshot action, and
 // marks the snapshot with the given snapshot ID as deleted.
 func (chk *Checker) DeleteSnapshot(ctx context.Context, snapID string) error {
@@ -232,13 +294,17 @@ func (chk *Checker) DeleteSnapshot(ctx context.Context, snapID string) error {
 		return err
 	}

-	ssMeta.DeletionTime = clock.Now()
+	ssMeta.DeletionTime = time.Now()
+	ssMeta.ValidationData = nil

 	err = chk.saveSnapshotMetadata(ssMeta)
 	if err != nil {
 		return err
 	}

+	chk.snapshotMetadataStore.AddToIndex(ssMeta.SnapID, deletedSnapshotsIdxName)
+	chk.snapshotMetadataStore.RemoveFromIndex(ssMeta.SnapID, liveSnapshotsIdxName)
+
 	return nil
 }

--- a/tests/robustness/engine/action.go
+++ b/tests/robustness/engine/action.go
@@ -0,0 +1,489 @@
+// +build darwin,amd64 linux,amd64
+
+package engine
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"log"
+	"math/rand"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/kopia/kopia/tests/tools/fio"
+)
+
+// Errors associated with action-picking.
+var (
+	ErrNoActionPicked = errors.New("unable to pick an action with the action control options provided")
+	ErrInvalidOption  = errors.New("invalid option setting")
+)
+
+// ExecAction executes the action denoted by the provided ActionKey.
+func (e *Engine) ExecAction(actionKey ActionKey, opts map[string]string) (map[string]string, error) {
+	if opts == nil {
+		opts = make(map[string]string)
+	}
+
+	e.RunStats.ActionCounter++
+	e.CumulativeStats.ActionCounter++
+	log.Printf("Engine executing ACTION: name=%q actionCount=%v totActCount=%v t=%vs (%vs)", actionKey, e.RunStats.ActionCounter, e.CumulativeStats.ActionCounter, e.RunStats.getLifetimeSeconds(), e.getRuntimeSeconds())
+
+	action := actions[actionKey]
+	st := time.Now()
+
+	logEntry := &LogEntry{
+		StartTime:       st,
+		EngineTimestamp: e.getTimestampS(),
+		Action:          actionKey,
+		ActionOpts:      opts,
+	}
+
+	// Execute the action n times
+	err := ErrNoOp // Default to no-op error
+
+	// TODO: return more than the last output
+	var out map[string]string
+
+	n := getOptAsIntOrDefault(ActionRepeaterField, opts, defaultActionRepeats)
+	for i := 0; i < n; i++ {
+		out, err = action.f(e, opts, logEntry)
+		if err != nil {
+			break
+		}
+	}
+
+	// If error was just a no-op, don't bother logging the action
+	switch {
+	case errors.Is(err, ErrNoOp):
+		e.RunStats.NoOpCount++
+		e.CumulativeStats.NoOpCount++
+
+		return out, err
+
+	case err != nil:
+		log.Printf("error=%q", err.Error())
+	}
+
+	if e.RunStats.PerActionStats != nil && e.RunStats.PerActionStats[actionKey] == nil {
+		e.RunStats.PerActionStats[actionKey] = new(ActionStats)
+	}
+
+	if e.CumulativeStats.PerActionStats != nil && e.CumulativeStats.PerActionStats[actionKey] == nil {
+		e.CumulativeStats.PerActionStats[actionKey] = new(ActionStats)
+	}
+
+	e.RunStats.PerActionStats[actionKey].Record(st, err)
+	e.CumulativeStats.PerActionStats[actionKey].Record(st, err)
+
+	e.EngineLog.AddCompleted(logEntry, err)
+
+	return out, err
+}
+
+// RandomAction executes a random action picked by the relative weights given
+// in actionOpts[ActionControlActionKey], or uniform probability if that
+// key is not present in the input options.
+func (e *Engine) RandomAction(actionOpts ActionOpts) error {
+	actionControlOpts := actionOpts.getActionControlOpts()
+
+	actionName := pickActionWeighted(actionControlOpts, actions)
+	if string(actionName) == "" {
+		return ErrNoActionPicked
+	}
+
+	_, err := e.ExecAction(actionName, actionOpts[actionName])
+	err = e.checkErrRecovery(err, actionOpts)
+
+	return err
+}
+
+func (e *Engine) checkErrRecovery(incomingErr error, actionOpts ActionOpts) (outgoingErr error) {
+	outgoingErr = incomingErr
+
+	if incomingErr == nil {
+		return nil
+	}
+
+	ctrl := actionOpts.getActionControlOpts()
+
+	if errIsNotEnoughSpace(incomingErr) && ctrl[ThrowNoSpaceOnDeviceErrField] == "" {
+		// no space left on device
+		// Delete everything in the data directory
+		const hundredPcnt = 100
+
+		deleteDirActionKey := DeleteDirectoryContentsActionKey
+		deleteRootOpts := map[string]string{
+			MaxDirDepthField:             strconv.Itoa(0),
+			DeletePercentOfContentsField: strconv.Itoa(hundredPcnt),
+		}
+
+		_, outgoingErr = e.ExecAction(deleteDirActionKey, deleteRootOpts)
+		if outgoingErr != nil {
+			return outgoingErr
+		}
+
+		e.RunStats.DataPurgeCount++
+		e.CumulativeStats.DataPurgeCount++
+
+		// Restore a previoius snapshot to the data directory
+		restoreActionKey := RestoreIntoDataDirectoryActionKey
+		_, outgoingErr = e.ExecAction(restoreActionKey, actionOpts[restoreActionKey])
+
+		if errors.Is(outgoingErr, ErrNoOp) {
+			outgoingErr = nil
+		} else {
+			e.RunStats.DataRestoreCount++
+			e.CumulativeStats.DataRestoreCount++
+		}
+	}
+
+	if outgoingErr == nil {
+		e.RunStats.ErrorRecoveryCount++
+		e.CumulativeStats.ErrorRecoveryCount++
+	}
+
+	return outgoingErr
+}
+
+// List of action keys.
+const (
+	ActionControlActionKey            ActionKey = "action-control"
+	SnapshotRootDirActionKey          ActionKey = "snapshot-root"
+	RestoreSnapshotActionKey          ActionKey = "restore-random-snapID"
+	DeleteRandomSnapshotActionKey     ActionKey = "delete-random-snapID"
+	WriteRandomFilesActionKey         ActionKey = "write-random-files"
+	DeleteRandomSubdirectoryActionKey ActionKey = "delete-random-subdirectory"
+	DeleteDirectoryContentsActionKey  ActionKey = "delete-files"
+	RestoreIntoDataDirectoryActionKey ActionKey = "restore-into-data-dir"
+	GCActionKey                       ActionKey = "run-gc"
+)
+
+// ActionOpts is a structure that designates the options for
+// picking and running an action.
+type ActionOpts map[ActionKey]map[string]string
+
+func (actionOpts ActionOpts) getActionControlOpts() map[string]string {
+	actionControlOpts := defaultActionControls()
+	if actionOpts != nil && actionOpts[ActionControlActionKey] != nil {
+		actionControlOpts = actionOpts[ActionControlActionKey]
+	}
+
+	return actionControlOpts
+}
+
+// Action is a unit of functionality that can be executed by
+// the engine.
+type Action struct {
+	f func(eng *Engine, opts map[string]string, l *LogEntry) (out map[string]string, err error)
+}
+
+// ActionKey refers to an action that can be executed by the engine.
+type ActionKey string
+
+var actions = map[ActionKey]Action{
+	SnapshotRootDirActionKey: {
+		f: func(e *Engine, opts map[string]string, l *LogEntry) (out map[string]string, err error) {
+			log.Printf("Creating snapshot of root directory %s", e.FileWriter.LocalDataDir)
+
+			ctx := context.TODO()
+			snapID, err := e.Checker.TakeSnapshot(ctx, e.FileWriter.LocalDataDir)
+
+			setLogEntryCmdOpts(l, map[string]string{
+				"snap-dir": e.FileWriter.LocalDataDir,
+				"snapID":   snapID,
+			})
+
+			return map[string]string{
+				SnapshotIDField: snapID,
+			}, err
+		},
+	},
+	RestoreSnapshotActionKey: {
+		f: func(e *Engine, opts map[string]string, l *LogEntry) (out map[string]string, err error) {
+			snapID, err := e.getSnapIDOptOrRandLive(opts)
+			if err != nil {
+				return nil, err
+			}
+
+			setLogEntryCmdOpts(l, map[string]string{"snapID": snapID})
+
+			log.Printf("Restoring snapshot %s", snapID)
+
+			ctx := context.Background()
+			b := &bytes.Buffer{}
+
+			err = e.Checker.RestoreSnapshot(ctx, snapID, b)
+			if err != nil {
+				log.Print(b.String())
+			}
+
+			return nil, err
+		},
+	},
+	DeleteRandomSnapshotActionKey: {
+		f: func(e *Engine, opts map[string]string, l *LogEntry) (out map[string]string, err error) {
+			snapID, err := e.getSnapIDOptOrRandLive(opts)
+			if err != nil {
+				return nil, err
+			}
+
+			log.Printf("Deleting snapshot %s", snapID)
+
+			setLogEntryCmdOpts(l, map[string]string{"snapID": snapID})
+
+			ctx := context.Background()
+			err = e.Checker.DeleteSnapshot(ctx, snapID)
+			return nil, err
+		},
+	},
+	GCActionKey: {
+		f: func(e *Engine, opts map[string]string, l *LogEntry) (out map[string]string, err error) {
+			return nil, e.TestRepo.RunGC()
+		},
+	},
+	WriteRandomFilesActionKey: {
+		f: func(e *Engine, opts map[string]string, l *LogEntry) (out map[string]string, err error) {
+			// Directory depth
+			maxDirDepth := getOptAsIntOrDefault(MaxDirDepthField, opts, defaultMaxDirDepth)
+			dirDepth := rand.Intn(maxDirDepth + 1) //nolint:gosec
+
+			// File size range
+			maxFileSizeB := getOptAsIntOrDefault(MaxFileSizeField, opts, defaultMaxFileSize)
+			minFileSizeB := getOptAsIntOrDefault(MinFileSizeField, opts, defaultMinFileSize)
+
+			// Number of files to write
+			maxNumFiles := getOptAsIntOrDefault(MaxNumFilesPerWriteField, opts, defaultMaxNumFilesPerWrite)
+			minNumFiles := getOptAsIntOrDefault(MinNumFilesPerWriteField, opts, defaultMinNumFilesPerWrite)
+
+			numFiles := rand.Intn(maxNumFiles-minNumFiles+1) + minNumFiles //nolint:gosec
+
+			// Dedup Percentage
+			maxDedupPcnt := getOptAsIntOrDefault(MaxDedupePercentField, opts, defaultMaxDedupePercent)
+			minDedupPcnt := getOptAsIntOrDefault(MinDedupePercentField, opts, defaultMinDedupePercent)
+
+			dedupStep := getOptAsIntOrDefault(DedupePercentStepField, opts, defaultDedupePercentStep)
+
+			dedupPcnt := dedupStep * (rand.Intn(maxDedupPcnt/dedupStep-minDedupPcnt/dedupStep+1) + minDedupPcnt/dedupStep) //nolint:gosec
+
+			blockSize := int64(defaultMinFileSize)
+
+			fioOpts := fio.Options{}.
+				WithFileSizeRange(int64(minFileSizeB), int64(maxFileSizeB)).
+				WithNumFiles(numFiles).
+				WithBlockSize(blockSize).
+				WithDedupePercentage(dedupPcnt).
+				WithNoFallocate()
+
+			ioLimit := getOptAsIntOrDefault(IOLimitPerWriteAction, opts, defaultIOLimitPerWriteAction)
+
+			if ioLimit > 0 {
+				freeSpaceLimitB := getOptAsIntOrDefault(FreeSpaceLimitField, opts, defaultFreeSpaceLimit)
+
+				freeSpaceB, err := getFreeSpaceB(e.FileWriter.LocalDataDir)
+				if err != nil {
+					return nil, err
+				}
+				log.Printf("Free Space %v B, limit %v B, ioLimit %v B\n", freeSpaceB, freeSpaceLimitB, ioLimit)
+
+				if int(freeSpaceB)-ioLimit < freeSpaceLimitB {
+					ioLimit = int(freeSpaceB) - freeSpaceLimitB
+					log.Printf("Cutting down I/O limit for space %v", ioLimit)
+					if ioLimit <= 0 {
+						return nil, ErrCannotPerformIO
+					}
+				}
+
+				fioOpts = fioOpts.WithIOLimit(int64(ioLimit))
+			}
+
+			relBasePath := "."
+
+			log.Printf("Writing files at depth %v (fileSize: %v-%v, numFiles: %v, blockSize: %v, dedupPcnt: %v, ioLimit: %v)\n", dirDepth, minFileSizeB, maxFileSizeB, numFiles, blockSize, dedupPcnt, ioLimit)
+
+			setLogEntryCmdOpts(l, map[string]string{
+				"dirDepth":    strconv.Itoa(dirDepth),
+				"relBasePath": relBasePath,
+			})
+
+			for k, v := range fioOpts {
+				l.CmdOpts[k] = v
+			}
+
+			return nil, e.FileWriter.WriteFilesAtDepthRandomBranch(relBasePath, dirDepth, fioOpts)
+		},
+	},
+	DeleteRandomSubdirectoryActionKey: {
+		f: func(e *Engine, opts map[string]string, l *LogEntry) (out map[string]string, err error) {
+			maxDirDepth := getOptAsIntOrDefault(MaxDirDepthField, opts, defaultMaxDirDepth)
+			if maxDirDepth <= 0 {
+				return nil, ErrInvalidOption
+			}
+			dirDepth := rand.Intn(maxDirDepth) + 1 //nolint:gosec
+
+			log.Printf("Deleting directory at depth %v\n", dirDepth)
+
+			setLogEntryCmdOpts(l, map[string]string{"dirDepth": strconv.Itoa(dirDepth)})
+
+			err = e.FileWriter.DeleteDirAtDepth("", dirDepth)
+			if errors.Is(err, fio.ErrNoDirFound) {
+				log.Print(err)
+				return nil, ErrNoOp
+			}
+
+			return nil, err
+		},
+	},
+	DeleteDirectoryContentsActionKey: {
+		f: func(e *Engine, opts map[string]string, l *LogEntry) (out map[string]string, err error) {
+			maxDirDepth := getOptAsIntOrDefault(MaxDirDepthField, opts, defaultMaxDirDepth)
+			dirDepth := rand.Intn(maxDirDepth + 1) //nolint:gosec
+
+			pcnt := getOptAsIntOrDefault(DeletePercentOfContentsField, opts, defaultDeletePercentOfContents)
+
+			log.Printf("Deleting %d%% of directory contents at depth %v\n", pcnt, dirDepth)
+
+			setLogEntryCmdOpts(l, map[string]string{
+				"dirDepth": strconv.Itoa(dirDepth),
+				"percent":  strconv.Itoa(pcnt),
+			})
+
+			const pcntConv = 100
+			err = e.FileWriter.DeleteContentsAtDepth("", dirDepth, float32(pcnt)/pcntConv)
+			if errors.Is(err, fio.ErrNoDirFound) {
+				log.Print(err)
+				return nil, ErrNoOp
+			}
+
+			return nil, err
+		},
+	},
+	RestoreIntoDataDirectoryActionKey: {
+		f: func(e *Engine, opts map[string]string, l *LogEntry) (out map[string]string, err error) {
+			snapID, err := e.getSnapIDOptOrRandLive(opts)
+			if err != nil {
+				return nil, err
+			}
+
+			log.Printf("Restoring snap ID %v into data directory\n", snapID)
+
+			setLogEntryCmdOpts(l, map[string]string{"snapID": snapID})
+
+			b := &bytes.Buffer{}
+			err = e.Checker.RestoreSnapshotToPath(context.Background(), snapID, e.FileWriter.LocalDataDir, b)
+			if err != nil {
+				log.Print(b.String())
+				return nil, err
+			}
+
+			return nil, nil
+		},
+	},
+}
+
+// Action constants.
+const (
+	defaultMaxDirDepth             = 20
+	defaultMaxFileSize             = 1 * 1024 * 1024 * 1024 // 1GB
+	defaultMinFileSize             = 4096
+	defaultMaxNumFilesPerWrite     = 10000
+	defaultMinNumFilesPerWrite     = 1
+	defaultIOLimitPerWriteAction   = 0                 // A zero value does not impose any limit on IO
+	defaultFreeSpaceLimit          = 100 * 1024 * 1024 // 100 MB
+	defaultMaxDedupePercent        = 100
+	defaultMinDedupePercent        = 0
+	defaultDedupePercentStep       = 25
+	defaultDeletePercentOfContents = 20
+	defaultActionRepeats           = 1
+)
+
+// Option field names.
+const (
+	MaxDirDepthField             = "max-dir-depth"
+	MaxFileSizeField             = "max-file-size"
+	MinFileSizeField             = "min-file-size"
+	MaxNumFilesPerWriteField     = "max-num-files-per-write"
+	MinNumFilesPerWriteField     = "min-num-files-per-write"
+	IOLimitPerWriteAction        = "io-limit-per-write"
+	FreeSpaceLimitField          = "free-space-limit"
+	MaxDedupePercentField        = "max-dedupe-percent"
+	MinDedupePercentField        = "min-dedupe-percent"
+	DedupePercentStepField       = "dedupe-percent"
+	ActionRepeaterField          = "repeat-action"
+	ThrowNoSpaceOnDeviceErrField = "throw-no-space-error"
+	DeletePercentOfContentsField = "delete-contents-percent"
+	SnapshotIDField              = "snapshot-ID"
+)
+
+func getOptAsIntOrDefault(key string, opts map[string]string, def int) int {
+	if opts == nil {
+		return def
+	}
+
+	if opts[key] == "" {
+		return def
+	}
+
+	retInt, err := strconv.Atoi(opts[key])
+	if err != nil {
+		return def
+	}
+
+	return retInt
+}
+
+func defaultActionControls() map[string]string {
+	ret := make(map[string]string, len(actions))
+
+	for actionKey := range actions {
+		switch actionKey {
+		case RestoreIntoDataDirectoryActionKey:
+			// Don't restore into data directory by default
+			ret[string(actionKey)] = strconv.Itoa(0)
+		default:
+			ret[string(actionKey)] = strconv.Itoa(1)
+		}
+	}
+
+	return ret
+}
+
+func pickActionWeighted(actionControlOpts map[string]string, actionList map[ActionKey]Action) ActionKey {
+	var keepKey ActionKey
+
+	sum := 0
+
+	for actionName := range actionList {
+		weight := getOptAsIntOrDefault(string(actionName), actionControlOpts, 0)
+		if weight == 0 {
+			continue
+		}
+
+		sum += weight
+		if rand.Intn(sum) < weight { //nolint:gosec
+			keepKey = actionName
+		}
+	}
+
+	return keepKey
+}
+
+func errIsNotEnoughSpace(err error) bool {
+	return errors.Is(err, ErrCannotPerformIO) || strings.Contains(err.Error(), noSpaceOnDeviceMatchStr)
+}
+
+func (e *Engine) getSnapIDOptOrRandLive(opts map[string]string) (snapID string, err error) {
+	snapID = opts[SnapshotIDField]
+	if snapID != "" {
+		return snapID, nil
+	}
+
+	snapIDList := e.Checker.GetLiveSnapIDs()
+	if len(snapIDList) == 0 {
+		return "", ErrNoOp
+	}
+
+	return snapIDList[rand.Intn(len(snapIDList))], nil //nolint:gosec
+}
--- a/tests/robustness/engine/engine.go
+++ b/tests/robustness/engine/engine.go
@@ -6,10 +6,14 @@
 import (
 	"context"
 	"fmt"
+	"io"
 	"io/ioutil"
-	"math/rand"
+	"log"
 	"os"
+	"path/filepath"
 	"strconv"
+	"strings"
+	"time"

 	"github.com/kopia/kopia/tests/robustness/checker"
 	"github.com/kopia/kopia/tests/robustness/snap"
@@ -24,8 +28,16 @@
 	S3BucketNameEnvKey = "S3_BUCKET_NAME"
 )

-// ErrS3BucketNameEnvUnset is the error returned when the S3BucketNameEnvKey environment variable is not set.
-var ErrS3BucketNameEnvUnset = fmt.Errorf("environment variable required: %v", S3BucketNameEnvKey)
+var (
+	// ErrNoOp is thrown when an action could not do anything useful.
+	ErrNoOp = fmt.Errorf("no-op")
+	// ErrCannotPerformIO is returned if the engine determines there is not enough space
+	// to write files.
+	ErrCannotPerformIO = fmt.Errorf("cannot perform i/o")
+	// ErrS3BucketNameEnvUnset is the error returned when the S3BucketNameEnvKey environment variable is not set.
+	ErrS3BucketNameEnvUnset = fmt.Errorf("environment variable required: %v", S3BucketNameEnvKey)
+	noSpaceOnDeviceMatchStr = "no space left on device"
+)

 // Engine is the outer level testing framework for robustness testing.
 type Engine struct {
@@ -34,6 +46,11 @@ type Engine struct {
 	MetaStore       snapmeta.Persister
 	Checker         *checker.Checker
 	cleanupRoutines []func()
+	baseDirPath     string
+
+	RunStats        Stats
+	CumulativeStats Stats
+	EngineLog       Log
 }

 // NewEngine instantiates a new Engine and returns its pointer. It is
@@ -48,12 +65,19 @@ func NewEngine(workingDir string) (*Engine, error) {
 		return nil, err
 	}

-	e := new(Engine)
+	e := &Engine{
+		baseDirPath: baseDirPath,
+		RunStats: Stats{
+			RunCounter:     1,
+			CreationTime:   time.Now(),
+			PerActionStats: make(map[ActionKey]*ActionStats),
+		},
+	}

 	// Fill the file writer
 	e.FileWriter, err = fio.NewRunner()
 	if err != nil {
-		e.Cleanup() //nolint:errcheck
+		e.CleanComponents()
 		return nil, err
 	}

@@ -62,7 +86,7 @@ func NewEngine(workingDir string) (*Engine, error) {
 	// Fill Snapshotter interface
 	kopiaSnapper, err := kopiarunner.NewKopiaSnapshotter(baseDirPath)
 	if err != nil {
-		e.Cleanup() //nolint:errcheck
+		e.CleanComponents()
 		return nil, err
 	}

@@ -72,7 +96,7 @@ func NewEngine(workingDir string) (*Engine, error) {
 	// Fill the snapshot store interface
 	snapStore, err := snapmeta.New(baseDirPath)
 	if err != nil {
-		e.Cleanup() //nolint:errcheck
+		e.CleanComponents()
 		return nil, err
 	}

@@ -80,12 +104,18 @@ func NewEngine(workingDir string) (*Engine, error) {

 	e.MetaStore = snapStore

+	err = e.setupLogging()
+	if err != nil {
+		e.CleanComponents()
+		return nil, err
+	}
+
 	// Create the data integrity checker
-	chk, err := checker.NewChecker(kopiaSnapper, snapStore, fswalker.NewWalkCompare())
+	chk, err := checker.NewChecker(kopiaSnapper, snapStore, fswalker.NewWalkCompare(), baseDirPath)
 	e.cleanupRoutines = append(e.cleanupRoutines, chk.Cleanup)

 	if err != nil {
-		e.Cleanup() //nolint:errcheck
+		e.CleanComponents()
 		return nil, err
 	}

@@ -96,18 +126,93 @@ func NewEngine(workingDir string) (*Engine, error) {

 // Cleanup cleans up after each component of the test engine.
 func (e *Engine) Cleanup() error {
-	defer e.cleanup()
+	// Perform a snapshot action to capture the state of the data directory
+	// at the end of the run
+	lastWriteEntry := e.EngineLog.FindLastThisRun(WriteRandomFilesActionKey)
+	lastSnapEntry := e.EngineLog.FindLastThisRun(SnapshotRootDirActionKey)
+
+	if lastWriteEntry != nil {
+		if lastSnapEntry == nil || lastSnapEntry.Idx < lastWriteEntry.Idx {
+			// Only force a final snapshot if the data tree has been modified since the last snapshot
+			e.ExecAction(SnapshotRootDirActionKey, make(map[string]string)) //nolint:errcheck
+		}
+	}
+
+	cleanupSummaryBuilder := new(strings.Builder)
+	cleanupSummaryBuilder.WriteString("\n================\n")
+	cleanupSummaryBuilder.WriteString("Cleanup Summary:\n\n")
+	cleanupSummaryBuilder.WriteString(e.Stats())
+	cleanupSummaryBuilder.WriteString("\n\n")
+	cleanupSummaryBuilder.WriteString(e.EngineLog.StringThisRun())
+	cleanupSummaryBuilder.WriteString("\n")
+
+	log.Print(cleanupSummaryBuilder.String())
+
+	e.RunStats.RunTime = time.Since(e.RunStats.CreationTime)
+	e.CumulativeStats.RunTime += e.RunStats.RunTime
+
+	defer e.CleanComponents()

 	if e.MetaStore != nil {
+		err := e.SaveLog()
+		if err != nil {
+			return err
+		}
+
+		err = e.SaveStats()
+		if err != nil {
+			return err
+		}
+
 		return e.MetaStore.FlushMetadata()
 	}

 	return nil
 }

-func (e *Engine) cleanup() {
+func (e *Engine) setupLogging() error {
+	dirPath := e.MetaStore.GetPersistDir()
+
+	newLogPath := filepath.Join(dirPath, e.formatLogName())
+
+	f, err := os.Create(newLogPath)
+	if err != nil {
+		return err
+	}
+
+	// Write to both stderr and persistent log file
+	wrt := io.MultiWriter(os.Stderr, f)
+	log.SetOutput(wrt)
+
+	return nil
+}
+
+func (e *Engine) formatLogName() string {
+	st := e.RunStats.CreationTime
+	return fmt.Sprintf("Log_%s", st.Format("2006_01_02_15_04_05"))
+}
+
+// CleanComponents cleans up each component part of the test engine.
+func (e *Engine) CleanComponents() {
 	for _, f := range e.cleanupRoutines {
-		f()
+		if f != nil {
+			f()
+		}
+	}
+
+	os.RemoveAll(e.baseDirPath) //nolint:errcheck
+}
+
+// Init initializes the Engine to a repository location according to the environment setup.
+// - If S3_BUCKET_NAME is set, initialize S3
+// - Else initialize filesystem.
+func (e *Engine) Init(ctx context.Context, testRepoPath, metaRepoPath string) error {
+	switch {
+	case os.Getenv(S3BucketNameEnvKey) != "":
+		bucketName := os.Getenv(S3BucketNameEnvKey)
+		return e.InitS3(ctx, bucketName, testRepoPath, metaRepoPath)
+	default:
+		return e.InitFilesystem(ctx, testRepoPath, metaRepoPath)
 	}
 }

@@ -115,48 +220,18 @@ func (e *Engine) cleanup() {
 // is successful, the engine is populated with the metadata associated with the
 // snapshot in that repo. A new repo will be created if one does not already
 // exist.
-func (e *Engine) InitS3(ctx context.Context, testRepoPath, metaRepoPath string) error {
-	bucketName := os.Getenv(S3BucketNameEnvKey)
-	if bucketName == "" {
-		return ErrS3BucketNameEnvUnset
-	}
-
+func (e *Engine) InitS3(ctx context.Context, bucketName, testRepoPath, metaRepoPath string) error {
 	err := e.MetaStore.ConnectOrCreateS3(bucketName, metaRepoPath)
 	if err != nil {
 		return err
 	}

-	err = e.MetaStore.LoadMetadata()
-	if err != nil {
-		return err
-	}
-
 	err = e.TestRepo.ConnectOrCreateS3(bucketName, testRepoPath)
 	if err != nil {
 		return err
 	}

-	_, _, err = e.TestRepo.Run("policy", "set", "--global", "--keep-latest", strconv.Itoa(1<<31-1))
-	if err != nil {
-		return err
-	}
-
-	err = e.Checker.VerifySnapshotMetadata()
-	if err != nil {
-		return err
-	}
-
-	snapIDs := e.Checker.GetLiveSnapIDs()
-	if len(snapIDs) > 0 {
-		randSnapID := snapIDs[rand.Intn(len(snapIDs))] //nolint:gosec
-
-		err = e.Checker.RestoreSnapshotToPath(ctx, randSnapID, e.FileWriter.LocalDataDir, os.Stdout)
-		if err != nil {
-			return err
-		}
-	}
-
-	return nil
+	return e.init(ctx)
 }

 // InitFilesystem attempts to connect to a test repo and metadata repo on the local
@@ -169,30 +244,36 @@ func (e *Engine) InitFilesystem(ctx context.Context, testRepoPath, metaRepoPath
 		return err
 	}

-	err = e.MetaStore.LoadMetadata()
-	if err != nil {
-		return err
-	}
-
 	err = e.TestRepo.ConnectOrCreateFilesystem(testRepoPath)
 	if err != nil {
 		return err
 	}

-	err = e.Checker.VerifySnapshotMetadata()
+	return e.init(ctx)
+}
+
+func (e *Engine) init(ctx context.Context) error {
+	err := e.MetaStore.LoadMetadata()
 	if err != nil {
 		return err
 	}

-	snapIDs := e.Checker.GetSnapIDs()
-	if len(snapIDs) > 0 {
-		randSnapID := snapIDs[rand.Intn(len(snapIDs))] //nolint:gosec
-
-		err = e.Checker.RestoreSnapshotToPath(ctx, randSnapID, e.FileWriter.LocalDataDir, os.Stdout)
-		if err != nil {
-			return err
-		}
+	err = e.LoadStats()
+	if err != nil {
+		return err
 	}

-	return nil
+	e.CumulativeStats.RunCounter++
+
+	err = e.LoadLog()
+	if err != nil {
+		return err
+	}
+
+	_, _, err = e.TestRepo.Run("policy", "set", "--global", "--keep-latest", strconv.Itoa(1<<31-1), "--compression", "s2-default")
+	if err != nil {
+		return err
+	}
+
+	return e.Checker.VerifySnapshotMetadata()
 }
--- a/tests/robustness/engine/engine_test.go
+++ b/tests/robustness/engine/engine_test.go
@@ -5,13 +5,23 @@

 import (
 	"context"
+	"crypto/rand"
+	"encoding/hex"
 	"errors"
 	"fmt"
+	"io"
 	"io/ioutil"
+	"math"
 	"os"
 	"path/filepath"
+	"strconv"
 	"testing"
+	"time"

+	"github.com/minio/minio-go/v6"
+	"github.com/minio/minio-go/v6/pkg/credentials"
+
+	"github.com/kopia/kopia/tests/robustness/snapmeta"
 	"github.com/kopia/kopia/tests/testenv"
 	"github.com/kopia/kopia/tests/tools/fio"
 	"github.com/kopia/kopia/tests/tools/fswalker"
@@ -19,10 +29,17 @@
 )

 var (
-	fsMetadataRepoPath = filepath.Join("/tmp", "metadata-repo")
-	s3MetadataRepoPath = filepath.Join("some/path", "metadata-repo")
-	fsDataRepoPath     = filepath.Join("/tmp", "data-repo")
-	s3DataRepoPath     = filepath.Join("some/path", "data-repo")
+	repoBaseDirName    = "engine"
+	fsBasePath         = "/tmp"
+	s3BasePath         = ""
+	dataRepoPath       = "unit-tests/data-repo"
+	metadataRepoPath   = "unit-tests/metadata-repo"
+	fsRepoBaseDirPath  = filepath.Join(fsBasePath, repoBaseDirName)
+	s3RepoBaseDirPath  = filepath.Join(s3BasePath, repoBaseDirName)
+	fsMetadataRepoPath = filepath.Join(fsRepoBaseDirPath, metadataRepoPath)
+	s3MetadataRepoPath = filepath.Join(s3RepoBaseDirPath, metadataRepoPath)
+	fsDataRepoPath     = filepath.Join(fsRepoBaseDirPath, dataRepoPath)
+	s3DataRepoPath     = filepath.Join(s3RepoBaseDirPath, dataRepoPath)
 )

 func TestEngineWritefilesBasicFS(t *testing.T) {
@@ -36,18 +53,20 @@ func TestEngineWritefilesBasicFS(t *testing.T) {
 	defer func() {
 		cleanupErr := eng.Cleanup()
 		testenv.AssertNoError(t, cleanupErr)
+
+		os.RemoveAll(fsRepoBaseDirPath)
 	}()

 	ctx := context.TODO()
 	err = eng.InitFilesystem(ctx, fsDataRepoPath, fsMetadataRepoPath)
 	testenv.AssertNoError(t, err)

-	fileSize := int64(256 * 1024 * 1024)
+	fileSize := int64(256 * 1024)
 	numFiles := 10

-	fioOpt := fio.Options{}.WithFileSize(fileSize).WithNumFiles(numFiles)
+	fioOpts := fio.Options{}.WithFileSize(fileSize).WithNumFiles(numFiles)

-	err = eng.FileWriter.WriteFiles("", fioOpt)
+	err = eng.FileWriter.WriteFiles("", fioOpts)
 	testenv.AssertNoError(t, err)

 	snapIDs := eng.Checker.GetSnapIDs()
@@ -64,7 +83,74 @@ func TestEngineWritefilesBasicFS(t *testing.T) {
 	}
 }

+func randomString(n int) string {
+	b := make([]byte, n)
+	io.ReadFull(rand.Reader, b)
+
+	return hex.EncodeToString(b)
+}
+
+func makeTempS3Bucket(t *testing.T) (bucketName string, cleanupCB func()) {
+	endpoint := "s3.amazonaws.com"
+	accessKeyID := os.Getenv("AWS_ACCESS_KEY_ID")
+	secretAccessKey := os.Getenv("AWS_SECRET_ACCESS_KEY")
+	sessionToken := os.Getenv("AWS_SESSION_TOKEN")
+
+	if accessKeyID == "" || secretAccessKey == "" || sessionToken == "" {
+		t.Skip("Skipping S3 tests if no creds provided")
+	}
+
+	secure := true
+	region := ""
+	cli, err := minio.NewWithCredentials(endpoint, credentials.NewStaticV4(accessKeyID, secretAccessKey, sessionToken), secure, region)
+	testenv.AssertNoError(t, err)
+
+	bucketName = fmt.Sprintf("engine-unit-tests-%s", randomString(4))
+	err = cli.MakeBucket(bucketName, "")
+	testenv.AssertNoError(t, err)
+
+	return bucketName, func() {
+		objNameCh := make(chan string)
+		errCh := cli.RemoveObjects(bucketName, objNameCh)
+
+		go func() {
+			for removeErr := range errCh {
+				t.Errorf("error removing key %s from bucket: %s", removeErr.ObjectName, removeErr.Err)
+			}
+		}()
+
+		recursive := true
+		doneCh := make(chan struct{})
+
+		defer close(doneCh)
+
+		for obj := range cli.ListObjects(bucketName, "", recursive, doneCh) {
+			objNameCh <- obj.Key
+		}
+
+		close(objNameCh)
+
+		retries := 10
+		retryPeriod := 1 * time.Second
+
+		var err error
+
+		for retry := 0; retry < retries; retry++ {
+			time.Sleep(retryPeriod)
+
+			err = cli.RemoveBucket(bucketName)
+			if err == nil {
+				break
+			}
+		}
+		testenv.AssertNoError(t, err)
+	}
+}
+
 func TestWriteFilesBasicS3(t *testing.T) {
+	bucketName, cleanupCB := makeTempS3Bucket(t)
+	defer cleanupCB()
+
 	eng, err := NewEngine("")
 	if err == kopiarunner.ErrExeVariableNotSet || errors.Is(err, fio.ErrEnvNotSet) {
 		t.Skip(err)
@@ -78,15 +164,15 @@ func TestWriteFilesBasicS3(t *testing.T) {
 	}()

 	ctx := context.TODO()
-	err = eng.InitS3(ctx, s3DataRepoPath, s3MetadataRepoPath)
+	err = eng.InitS3(ctx, bucketName, s3DataRepoPath, s3MetadataRepoPath)
 	testenv.AssertNoError(t, err)

-	fileSize := int64(256 * 1024 * 1024)
+	fileSize := int64(256 * 1024)
 	numFiles := 10

-	fioOpt := fio.Options{}.WithFileSize(fileSize).WithNumFiles(numFiles)
+	fioOpts := fio.Options{}.WithFileSize(fileSize).WithNumFiles(numFiles)

-	err = eng.FileWriter.WriteFiles("", fioOpt)
+	err = eng.FileWriter.WriteFiles("", fioOpts)
 	testenv.AssertNoError(t, err)

 	snapIDs := eng.Checker.GetLiveSnapIDs()
@@ -104,6 +190,9 @@ func TestWriteFilesBasicS3(t *testing.T) {
 }

 func TestDeleteSnapshotS3(t *testing.T) {
+	bucketName, cleanupCB := makeTempS3Bucket(t)
+	defer cleanupCB()
+
 	eng, err := NewEngine("")
 	if err == kopiarunner.ErrExeVariableNotSet || errors.Is(err, fio.ErrEnvNotSet) {
 		t.Skip(err)
@@ -117,15 +206,15 @@ func TestDeleteSnapshotS3(t *testing.T) {
 	}()

 	ctx := context.TODO()
-	err = eng.InitS3(ctx, s3DataRepoPath, s3MetadataRepoPath)
+	err = eng.InitS3(ctx, bucketName, s3DataRepoPath, s3MetadataRepoPath)
 	testenv.AssertNoError(t, err)

-	fileSize := int64(256 * 1024 * 1024)
+	fileSize := int64(256 * 1024)
 	numFiles := 10

-	fioOpt := fio.Options{}.WithFileSize(fileSize).WithNumFiles(numFiles)
+	fioOpts := fio.Options{}.WithFileSize(fileSize).WithNumFiles(numFiles)

-	err = eng.FileWriter.WriteFiles("", fioOpt)
+	err = eng.FileWriter.WriteFiles("", fioOpts)
 	testenv.AssertNoError(t, err)

 	snapID, err := eng.Checker.TakeSnapshot(ctx, eng.FileWriter.LocalDataDir)
@@ -144,6 +233,9 @@ func TestDeleteSnapshotS3(t *testing.T) {
 }

 func TestSnapshotVerificationFail(t *testing.T) {
+	bucketName, cleanupCB := makeTempS3Bucket(t)
+	defer cleanupCB()
+
 	eng, err := NewEngine("")
 	if err == kopiarunner.ErrExeVariableNotSet || errors.Is(err, fio.ErrEnvNotSet) {
 		t.Skip(err)
@@ -157,13 +249,12 @@ func TestSnapshotVerificationFail(t *testing.T) {
 	}()

 	ctx := context.TODO()
-	err = eng.InitS3(ctx, s3DataRepoPath, s3MetadataRepoPath)
+	err = eng.InitS3(ctx, bucketName, s3DataRepoPath, s3MetadataRepoPath)
 	testenv.AssertNoError(t, err)

 	// Perform writes
-	fileSize := int64(256 * 1024 * 1024)
+	fileSize := int64(256 * 1024)
 	numFiles := 10
-
 	fioOpt := fio.Options{}.WithFileSize(fileSize).WithNumFiles(numFiles)

 	err = eng.FileWriter.WriteFiles("", fioOpt)
@@ -230,7 +321,7 @@ func TestDataPersistency(t *testing.T) {
 	testenv.AssertNoError(t, err)

 	// Perform writes
-	fileSize := int64(256 * 1024 * 1024)
+	fileSize := int64(256 * 1024)
 	numFiles := 10

 	fioOpt := fio.Options{}.WithFileSize(fileSize).WithNumFiles(numFiles)
@@ -254,7 +345,7 @@ func TestDataPersistency(t *testing.T) {
 	eng2, err := NewEngine("")
 	testenv.AssertNoError(t, err)

-	defer eng2.cleanup()
+	defer eng2.CleanComponents()

 	// Connect this engine to the same data and metadata repositories -
 	// expect that the snapshot taken above will be found in metadata,
@@ -263,8 +354,382 @@ func TestDataPersistency(t *testing.T) {
 	err = eng2.InitFilesystem(ctx, dataRepoPath, metadataRepoPath)
 	testenv.AssertNoError(t, err)

+	err = eng2.Checker.RestoreSnapshotToPath(ctx, snapID, eng2.FileWriter.LocalDataDir, os.Stdout)
+	testenv.AssertNoError(t, err)
+
 	// Compare the data directory of the second engine with the fingerprint
 	// of the snapshot taken earlier. They should match.
 	err = fswalker.NewWalkCompare().Compare(ctx, eng2.FileWriter.LocalDataDir, dataDirWalk.ValidationData, os.Stdout)
 	testenv.AssertNoError(t, err)
 }
+
+func TestPickActionWeighted(t *testing.T) {
+	for _, tc := range []struct {
+		name             string
+		inputCtrlWeights map[string]float64
+		inputActionList  map[ActionKey]Action
+	}{
+		{
+			name: "basic uniform",
+			inputCtrlWeights: map[string]float64{
+				"A": 1,
+				"B": 1,
+				"C": 1,
+			},
+			inputActionList: map[ActionKey]Action{
+				"A": {},
+				"B": {},
+				"C": {},
+			},
+		},
+		{
+			name: "basic weighted",
+			inputCtrlWeights: map[string]float64{
+				"A": 1,
+				"B": 10,
+				"C": 100,
+			},
+			inputActionList: map[ActionKey]Action{
+				"A": {},
+				"B": {},
+				"C": {},
+			},
+		},
+		{
+			name: "include a zero weight",
+			inputCtrlWeights: map[string]float64{
+				"A": 1,
+				"B": 0,
+				"C": 1,
+			},
+			inputActionList: map[ActionKey]Action{
+				"A": {},
+				"B": {},
+				"C": {},
+			},
+		},
+		{
+			name: "include an ActionKey that is not in the action list",
+			inputCtrlWeights: map[string]float64{
+				"A": 1,
+				"B": 1,
+				"C": 1,
+				"D": 100,
+			},
+			inputActionList: map[ActionKey]Action{
+				"A": {},
+				"B": {},
+				"C": {},
+			},
+		},
+	} {
+		t.Log(tc.name)
+
+		weightsSum := 0.0
+		inputCtrlOpts := make(map[string]string)
+
+		for k, v := range tc.inputCtrlWeights {
+			// Do not weight actions that are not expected in the results
+			if _, ok := tc.inputActionList[ActionKey(k)]; !ok {
+				continue
+			}
+
+			inputCtrlOpts[k] = strconv.Itoa(int(v))
+			weightsSum += v
+		}
+
+		numTestLoops := 100000
+
+		results := make(map[ActionKey]int, len(tc.inputCtrlWeights))
+		for loop := 0; loop < numTestLoops; loop++ {
+			results[pickActionWeighted(inputCtrlOpts, tc.inputActionList)]++
+		}
+
+		for actionKey, count := range results {
+			p := tc.inputCtrlWeights[string(actionKey)] / weightsSum
+			exp := p * float64(numTestLoops)
+
+			errPcnt := math.Abs(exp-float64(count)) / exp
+			if errPcnt > 0.1 {
+				t.Errorf("Error in actual counts was above 10%% for %v (exp %v, actual %v)", actionKey, exp, count)
+			}
+		}
+	}
+}
+
+func TestActionsFilesystem(t *testing.T) {
+	eng, err := NewEngine("")
+	if err == kopiarunner.ErrExeVariableNotSet || errors.Is(err, fio.ErrEnvNotSet) {
+		t.Skip(err)
+	}
+
+	testenv.AssertNoError(t, err)
+
+	defer func() {
+		cleanupErr := eng.Cleanup()
+		testenv.AssertNoError(t, cleanupErr)
+
+		os.RemoveAll(fsRepoBaseDirPath)
+	}()
+
+	ctx := context.TODO()
+	err = eng.InitFilesystem(ctx, fsDataRepoPath, fsMetadataRepoPath)
+	testenv.AssertNoError(t, err)
+
+	actionOpts := ActionOpts{
+		WriteRandomFilesActionKey: map[string]string{
+			MaxDirDepthField:         "20",
+			MaxFileSizeField:         strconv.Itoa(10 * 1024 * 1024),
+			MinFileSizeField:         strconv.Itoa(10 * 1024 * 1024),
+			MaxNumFilesPerWriteField: "10",
+			MinNumFilesPerWriteField: "10",
+			MaxDedupePercentField:    "100",
+			MinDedupePercentField:    "100",
+			DedupePercentStepField:   "1",
+			IOLimitPerWriteAction:    "0",
+		},
+	}
+
+	numActions := 10
+	for loop := 0; loop < numActions; loop++ {
+		err := eng.RandomAction(actionOpts)
+		if !(err == nil || err == ErrNoOp) {
+			t.Error("Hit error", err)
+		}
+	}
+}
+
+func TestActionsS3(t *testing.T) {
+	bucketName, cleanupCB := makeTempS3Bucket(t)
+	defer cleanupCB()
+
+	eng, err := NewEngine("")
+	if err == kopiarunner.ErrExeVariableNotSet || errors.Is(err, fio.ErrEnvNotSet) {
+		t.Skip(err)
+	}
+
+	testenv.AssertNoError(t, err)
+
+	defer func() {
+		cleanupErr := eng.Cleanup()
+		testenv.AssertNoError(t, cleanupErr)
+	}()
+
+	ctx := context.TODO()
+	err = eng.InitS3(ctx, bucketName, s3DataRepoPath, s3MetadataRepoPath)
+	testenv.AssertNoError(t, err)
+
+	actionOpts := ActionOpts{
+		WriteRandomFilesActionKey: map[string]string{
+			MaxDirDepthField:         "20",
+			MaxFileSizeField:         strconv.Itoa(10 * 1024 * 1024),
+			MinFileSizeField:         strconv.Itoa(10 * 1024 * 1024),
+			MaxNumFilesPerWriteField: "10",
+			MinNumFilesPerWriteField: "10",
+			MaxDedupePercentField:    "100",
+			MinDedupePercentField:    "100",
+			DedupePercentStepField:   "1",
+			IOLimitPerWriteAction:    "0",
+		},
+	}
+
+	numActions := 10
+	for loop := 0; loop < numActions; loop++ {
+		err := eng.RandomAction(actionOpts)
+		if !(err == nil || err == ErrNoOp) {
+			t.Error("Hit error", err)
+		}
+	}
+}
+
+func TestIOLimitPerWriteAction(t *testing.T) {
+	// Instruct a write action to write an enormous amount of data
+	// that should take longer than this timeout without "io_limit",
+	// but finish in less time with "io_limit". Command instructs fio
+	// to generate 100 files x 10 MB each = 1 GB of i/o. The limit is
+	// set to 1 MB.
+	const timeout = 10 * time.Second
+
+	eng, err := NewEngine("")
+	if err == kopiarunner.ErrExeVariableNotSet || errors.Is(err, fio.ErrEnvNotSet) {
+		t.Skip(err)
+	}
+
+	testenv.AssertNoError(t, err)
+
+	defer func() {
+		cleanupErr := eng.Cleanup()
+		testenv.AssertNoError(t, cleanupErr)
+
+		os.RemoveAll(fsRepoBaseDirPath)
+	}()
+
+	ctx := context.TODO()
+	err = eng.InitFilesystem(ctx, fsDataRepoPath, fsMetadataRepoPath)
+	testenv.AssertNoError(t, err)
+
+	actionOpts := ActionOpts{
+		ActionControlActionKey: map[string]string{
+			string(SnapshotRootDirActionKey):          strconv.Itoa(0),
+			string(RestoreSnapshotActionKey):          strconv.Itoa(0),
+			string(DeleteRandomSnapshotActionKey):     strconv.Itoa(0),
+			string(WriteRandomFilesActionKey):         strconv.Itoa(1),
+			string(DeleteRandomSubdirectoryActionKey): strconv.Itoa(0),
+		},
+		WriteRandomFilesActionKey: map[string]string{
+			MaxDirDepthField:         "2",
+			MaxFileSizeField:         strconv.Itoa(10 * 1024 * 1024),
+			MinFileSizeField:         strconv.Itoa(10 * 1024 * 1024),
+			MaxNumFilesPerWriteField: "100",
+			MinNumFilesPerWriteField: "100",
+			IOLimitPerWriteAction:    strconv.Itoa(1 * 1024 * 1024),
+		},
+	}
+
+	st := time.Now()
+
+	numActions := 1
+	for loop := 0; loop < numActions; loop++ {
+		err := eng.RandomAction(actionOpts)
+		testenv.AssertNoError(t, err)
+	}
+
+	if time.Since(st) > timeout {
+		t.Errorf("IO limit parameter did not cut down on the fio runtime")
+	}
+}
+
+func TestStatsPersist(t *testing.T) {
+	tmpDir, err := ioutil.TempDir("", "stats-persist-test")
+	testenv.AssertNoError(t, err)
+
+	defer os.RemoveAll(tmpDir)
+
+	snapStore, err := snapmeta.New(tmpDir)
+	if errors.Is(err, kopiarunner.ErrExeVariableNotSet) {
+		t.Skip(err)
+	}
+
+	testenv.AssertNoError(t, err)
+
+	err = snapStore.ConnectOrCreateFilesystem(tmpDir)
+	testenv.AssertNoError(t, err)
+
+	actionstats := &ActionStats{
+		Count:        120,
+		TotalRuntime: 25 * time.Hour,
+		MinRuntime:   5 * time.Minute,
+		MaxRuntime:   35 * time.Minute,
+	}
+
+	creationTime := time.Now().Add(-time.Hour)
+
+	eng := &Engine{
+		MetaStore: snapStore,
+		CumulativeStats: Stats{
+			ActionCounter: 11235,
+			CreationTime:  creationTime,
+			PerActionStats: map[ActionKey]*ActionStats{
+				ActionKey("some-action"): actionstats,
+			},
+			DataRestoreCount: 99,
+		},
+	}
+
+	err = eng.SaveStats()
+	testenv.AssertNoError(t, err)
+
+	err = eng.MetaStore.FlushMetadata()
+	testenv.AssertNoError(t, err)
+
+	snapStoreNew, err := snapmeta.New(tmpDir)
+	testenv.AssertNoError(t, err)
+
+	// Connect to the same metadata store
+	err = snapStoreNew.ConnectOrCreateFilesystem(tmpDir)
+	testenv.AssertNoError(t, err)
+
+	err = snapStoreNew.LoadMetadata()
+	testenv.AssertNoError(t, err)
+
+	engNew := &Engine{
+		MetaStore: snapStoreNew,
+	}
+
+	err = engNew.LoadStats()
+	testenv.AssertNoError(t, err)
+
+	if got, want := engNew.Stats(), eng.Stats(); got != want {
+		t.Errorf("Stats do not match\n%v\n%v", got, want)
+	}
+
+	fmt.Println(eng.Stats())
+	fmt.Println(engNew.Stats())
+}
+
+func TestLogsPersist(t *testing.T) {
+	tmpDir, err := ioutil.TempDir("", "logs-persist-test")
+	testenv.AssertNoError(t, err)
+
+	defer os.RemoveAll(tmpDir)
+
+	snapStore, err := snapmeta.New(tmpDir)
+	if errors.Is(err, kopiarunner.ErrExeVariableNotSet) {
+		t.Skip(err)
+	}
+
+	testenv.AssertNoError(t, err)
+
+	err = snapStore.ConnectOrCreateFilesystem(tmpDir)
+	testenv.AssertNoError(t, err)
+
+	log := Log{
+		Log: []*LogEntry{
+			{
+				StartTime: time.Now().Add(-time.Hour),
+				EndTime:   time.Now(),
+				Action:    ActionKey("some action"),
+				Error:     "some error",
+				Idx:       11235,
+				ActionOpts: map[string]string{
+					"opt1": "opt1 value",
+				},
+				CmdOpts: map[string]string{
+					"cmdOpt": "cmdOptVal",
+				},
+			},
+		},
+	}
+
+	eng := &Engine{
+		MetaStore: snapStore,
+		EngineLog: log,
+	}
+
+	err = eng.SaveLog()
+	testenv.AssertNoError(t, err)
+
+	err = eng.MetaStore.FlushMetadata()
+	testenv.AssertNoError(t, err)
+
+	snapStoreNew, err := snapmeta.New(tmpDir)
+	testenv.AssertNoError(t, err)
+
+	// Connect to the same metadata store
+	err = snapStoreNew.ConnectOrCreateFilesystem(tmpDir)
+	testenv.AssertNoError(t, err)
+
+	err = snapStoreNew.LoadMetadata()
+	testenv.AssertNoError(t, err)
+
+	engNew := &Engine{
+		MetaStore: snapStoreNew,
+	}
+
+	err = engNew.LoadLog()
+	testenv.AssertNoError(t, err)
+
+	if got, want := engNew.EngineLog.String(), eng.EngineLog.String(); got != want {
+		t.Errorf("Logs do not match\n%v\n%v", got, want)
+	}
+}
--- a/tests/robustness/engine/log.go
+++ b/tests/robustness/engine/log.go
@@ -0,0 +1,126 @@
+// +build darwin,amd64 linux,amd64
+
+package engine
+
+import (
+	"fmt"
+	"strings"
+	"time"
+)
+
+// Log keeps track of the actions taken by the engine.
+type Log struct {
+	runOffset int
+	Log       []*LogEntry
+}
+
+// LogEntry is an entry for the engine log.
+type LogEntry struct {
+	StartTime       time.Time
+	EndTime         time.Time
+	EngineTimestamp int64
+	Action          ActionKey
+	Error           string
+	Idx             int64
+	ActionOpts      map[string]string
+	CmdOpts         map[string]string
+}
+
+func (l *LogEntry) String() string {
+	b := &strings.Builder{}
+
+	const timeResol = 100 * time.Millisecond
+
+	fmt.Fprintf(b, "%4v t=%ds %s (%s): %v -> error=%s\n",
+		l.Idx,
+		l.EngineTimestamp,
+		formatTime(l.StartTime),
+		l.EndTime.Sub(l.StartTime).Round(timeResol),
+		l.Action,
+		l.Error,
+	)
+
+	return b.String()
+}
+
+func formatTime(tm time.Time) string {
+	return tm.Format("2006/01/02 15:04:05 MST")
+}
+
+// StringThisRun returns a string of only the log entries generated
+// by actions in this run of the engine.
+func (elog *Log) StringThisRun() string {
+	b := &strings.Builder{}
+
+	for i, l := range elog.Log {
+		if i >= elog.runOffset {
+			fmt.Fprint(b, l.String())
+		}
+	}
+
+	return b.String()
+}
+
+func (elog *Log) String() string {
+	b := &strings.Builder{}
+
+	fmt.Fprintf(b, "Log size:    %10v\n", len(elog.Log))
+	fmt.Fprintf(b, "========\n")
+
+	for _, l := range elog.Log {
+		fmt.Fprint(b, l.String())
+	}
+
+	return b.String()
+}
+
+// AddEntry adds a LogEntry to the Log.
+func (elog *Log) AddEntry(l *LogEntry) {
+	l.Idx = int64(len(elog.Log))
+	elog.Log = append(elog.Log, l)
+}
+
+// AddCompleted finalizes a log entry at the time it is called
+// and with the provided error, before adding it to the Log.
+func (elog *Log) AddCompleted(logEntry *LogEntry, err error) {
+	logEntry.EndTime = time.Now()
+	if err != nil {
+		logEntry.Error = err.Error()
+	}
+
+	elog.AddEntry(logEntry)
+
+	if len(elog.Log) == 0 {
+		panic("Did not get added")
+	}
+}
+
+// FindLast finds the most recent log entry with the provided ActionKey.
+func (elog *Log) FindLast(actionKey ActionKey) *LogEntry {
+	return elog.findLastUntilIdx(actionKey, 0)
+}
+
+// FindLastThisRun finds the most recent log entry with the provided ActionKey,
+// limited to the current run only.
+func (elog *Log) FindLastThisRun(actionKey ActionKey) (found *LogEntry) {
+	return elog.findLastUntilIdx(actionKey, elog.runOffset)
+}
+
+func (elog *Log) findLastUntilIdx(actionKey ActionKey, limitIdx int) *LogEntry {
+	for i := len(elog.Log) - 1; i >= limitIdx; i-- {
+		entry := elog.Log[i]
+		if entry != nil && entry.Action == actionKey {
+			return entry
+		}
+	}
+
+	return nil
+}
+
+func setLogEntryCmdOpts(l *LogEntry, opts map[string]string) {
+	if l == nil {
+		return
+	}
+
+	l.CmdOpts = opts
+}
--- a/tests/robustness/engine/metadata.go
+++ b/tests/robustness/engine/metadata.go
@@ -0,0 +1,77 @@
+// +build darwin,amd64 linux,amd64
+
+package engine
+
+import (
+	"encoding/json"
+	"errors"
+	"time"
+
+	"github.com/kopia/kopia/tests/robustness/snapmeta"
+)
+
+const (
+	engineStatsStoreKey = "cumulative-engine-stats"
+	engineLogsStoreKey  = "engine-logs"
+)
+
+// SaveLog saves the engine Log in the metadata store.
+func (e *Engine) SaveLog() error {
+	b, err := json.Marshal(e.EngineLog)
+	if err != nil {
+		return err
+	}
+
+	return e.MetaStore.Store(engineLogsStoreKey, b)
+}
+
+// LoadLog loads the engine log from the metadata store.
+func (e *Engine) LoadLog() error {
+	b, err := e.MetaStore.Load(engineLogsStoreKey)
+	if err != nil {
+		if errors.Is(err, snapmeta.ErrKeyNotFound) {
+			// Swallow key-not-found error. May not have historical logs
+			return nil
+		}
+
+		return err
+	}
+
+	err = json.Unmarshal(b, &e.EngineLog)
+	if err != nil {
+		return err
+	}
+
+	e.EngineLog.runOffset = len(e.EngineLog.Log)
+
+	return err
+}
+
+// SaveStats saves the engine Stats in the metadata store.
+func (e *Engine) SaveStats() error {
+	cumulStatRaw, err := json.Marshal(e.CumulativeStats)
+	if err != nil {
+		return err
+	}
+
+	return e.MetaStore.Store(engineStatsStoreKey, cumulStatRaw)
+}
+
+// LoadStats loads the engine Stats from the metadata store.
+func (e *Engine) LoadStats() error {
+	b, err := e.MetaStore.Load(engineStatsStoreKey)
+	if err != nil {
+		if errors.Is(err, snapmeta.ErrKeyNotFound) {
+			// Swallow key-not-found error. We may not have historical
+			// stats data. Initialize the action map for the cumulative stats
+			e.CumulativeStats.PerActionStats = make(map[ActionKey]*ActionStats)
+			e.CumulativeStats.CreationTime = time.Now()
+
+			return nil
+		}
+
+		return err
+	}
+
+	return json.Unmarshal(b, &e.CumulativeStats)
+}
--- a/tests/robustness/engine/stats.go
+++ b/tests/robustness/engine/stats.go
@@ -0,0 +1,155 @@
+// +build darwin,amd64 linux,amd64
+
+package engine
+
+import (
+	"fmt"
+	"strings"
+	"time"
+)
+
+var (
+	repoBuildTime   = "unknown"
+	repoGitRevision = "unknown"
+	repoGitBranch   = "unknown"
+	testBuildTime   = "unknown"
+	testGitRevision = "unknown"
+	testGitBranch   = "unknown"
+)
+
+// Stats prints the engine stats, cumulative and from the current run.
+func (e *Engine) Stats() string {
+	b := &strings.Builder{}
+
+	fmt.Fprintln(b, "==================================")
+	fmt.Fprintln(b, "Build Info")
+	fmt.Fprintln(b, "==================================")
+	fmt.Fprintf(b, "  Repo build time:      %25v\n", repoBuildTime)
+	fmt.Fprintf(b, "  Repo git revision:    %25v\n", repoGitRevision)
+	fmt.Fprintf(b, "  Repo git branch:      %25v\n", repoGitBranch)
+	fmt.Fprintln(b, "")
+	fmt.Fprintf(b, "  Engine build time:    %25v\n", testBuildTime)
+	fmt.Fprintf(b, "  Engine git revision:  %25v\n", testGitRevision)
+	fmt.Fprintf(b, "  Engine git branch:    %25v\n", testGitBranch)
+	fmt.Fprintln(b, "")
+	fmt.Fprintln(b, "==================================")
+	fmt.Fprintln(b, "Engine Action Summary (Cumulative)")
+	fmt.Fprintln(b, "==================================")
+	fmt.Fprintf(b, "  Engine runtime:   %10vs\n", e.getRuntimeSeconds())
+	fmt.Fprintln(b, "")
+	fmt.Fprint(b, e.CumulativeStats.Stats())
+	fmt.Fprintln(b, "")
+
+	fmt.Fprintln(b, "==================================")
+	fmt.Fprintln(b, "Engine Action Summary (This Run)")
+	fmt.Fprintln(b, "==================================")
+	fmt.Fprint(b, e.RunStats.Stats())
+	fmt.Fprintln(b, "")
+
+	return b.String()
+}
+
+// Stats tracks statistics during engine runtime.
+type Stats struct {
+	RunCounter     int64
+	ActionCounter  int64
+	CreationTime   time.Time
+	RunTime        time.Duration
+	PerActionStats map[ActionKey]*ActionStats
+
+	DataRestoreCount   int64
+	DataPurgeCount     int64
+	ErrorRecoveryCount int64
+	NoOpCount          int64
+}
+
+// Stats returns a string report of the engine's stats.
+func (stats *Stats) Stats() string {
+	b := &strings.Builder{}
+
+	fmt.Fprintln(b, "=============")
+	fmt.Fprintln(b, "Stat summary")
+	fmt.Fprintln(b, "=============")
+	fmt.Fprintf(b, "  Number of runs:     %10v\n", stats.RunCounter)
+	fmt.Fprintf(b, "  Engine lifetime:   %10vs\n", stats.getLifetimeSeconds())
+	fmt.Fprintf(b, "  Actions run:        %10v\n", stats.ActionCounter)
+	fmt.Fprintf(b, "  Errors recovered:   %10v\n", stats.ErrorRecoveryCount)
+	fmt.Fprintf(b, "  Data dir restores:  %10v\n", stats.DataRestoreCount)
+	fmt.Fprintf(b, "  Data dir purges:    %10v\n", stats.DataPurgeCount)
+	fmt.Fprintf(b, "  NoOp count:         %10v\n", stats.NoOpCount)
+	fmt.Fprintln(b, "")
+	fmt.Fprintln(b, "=============")
+	fmt.Fprintln(b, "Action stats")
+	fmt.Fprintln(b, "=============")
+
+	for actionKey, actionStat := range stats.PerActionStats {
+		fmt.Fprintf(b, "%s:\n", actionKey)
+		fmt.Fprintf(b, "  Count:            %10d\n", actionStat.Count)
+		fmt.Fprintf(b, "  Avg Runtime:      %10v\n", actionStat.avgRuntimeString())
+		fmt.Fprintf(b, "  Max Runtime:     %10vs\n", durationToSec(actionStat.MaxRuntime))
+		fmt.Fprintf(b, "  Min Runtime:     %10vs\n", durationToSec(actionStat.MinRuntime))
+		fmt.Fprintf(b, "  Error Count:      %10v\n", actionStat.ErrorCount)
+		fmt.Fprintln(b, "")
+	}
+
+	return b.String()
+}
+
+// ActionStats tracks runtime statistics for an action.
+type ActionStats struct {
+	Count        int64
+	TotalRuntime time.Duration
+	MinRuntime   time.Duration
+	MaxRuntime   time.Duration
+	ErrorCount   int64
+}
+
+// AverageRuntime returns the average run time for the action.
+func (s *ActionStats) AverageRuntime() time.Duration {
+	return time.Duration(int64(s.TotalRuntime) / s.Count)
+}
+
+// Record records the current time against the provided start time
+// and updates the stats accordingly.
+func (s *ActionStats) Record(st time.Time, err error) {
+	thisRuntime := time.Since(st)
+	s.TotalRuntime += thisRuntime
+
+	if thisRuntime > s.MaxRuntime {
+		s.MaxRuntime = thisRuntime
+	}
+
+	if s.Count == 0 || thisRuntime < s.MinRuntime {
+		s.MinRuntime = thisRuntime
+	}
+
+	s.Count++
+
+	if err != nil {
+		s.ErrorCount++
+	}
+}
+
+func (stats *Stats) getLifetimeSeconds() int64 {
+	return durationToSec(time.Since(stats.CreationTime))
+}
+
+func durationToSec(dur time.Duration) int64 {
+	return int64(dur.Round(time.Second).Seconds())
+}
+
+func (s *ActionStats) avgRuntimeString() string {
+	if s.Count == 0 {
+		return "--"
+	}
+
+	return fmt.Sprintf("%vs", durationToSec(s.AverageRuntime()))
+}
+
+func (e *Engine) getTimestampS() int64 {
+	return e.getRuntimeSeconds()
+}
+
+func (e *Engine) getRuntimeSeconds() int64 {
+	return durationToSec(e.CumulativeStats.RunTime + time.Since(e.RunStats.CreationTime))
+}
--- a/tests/robustness/engine/sys.go
+++ b/tests/robustness/engine/sys.go
@@ -0,0 +1,19 @@
+// +build darwin,amd64 linux,amd64
+
+package engine
+
+import (
+	"syscall"
+)
+
+func getFreeSpaceB(path string) (uint64, error) {
+	var stat syscall.Statfs_t
+
+	err := syscall.Statfs(path, &stat)
+	if err != nil {
+		return 0, err
+	}
+
+	// Available blocks * size per block = available space in bytes
+	return stat.Bavail * uint64(stat.Bsize), nil
+}
--- a/tests/robustness/robustness_test/main_test.go
+++ b/tests/robustness/robustness_test/main_test.go
@@ -5,9 +5,13 @@
 import (
 	"context"
 	"errors"
+	"flag"
+	"fmt"
 	"log"
 	"os"
+	"path"
 	"testing"
+	"time"

 	"github.com/kopia/kopia/tests/robustness/engine"
 	"github.com/kopia/kopia/tests/tools/fio"
@@ -17,38 +21,62 @@
 var eng *engine.Engine

 const (
-	fsDataPath     = "/tmp/robustness-data"
-	fsMetadataPath = "/tmp/robustness-metadata"
-	s3DataPath     = "robustness-data"
-	s3MetadataPath = "robustness-metadata"
+	dataSubPath     = "robustness-data"
+	metadataSubPath = "robustness-metadata"
+	defaultTestDur  = 5 * time.Minute
+)
+
+var (
+	randomizedTestDur = flag.Duration("rand-test-duration", defaultTestDur, "Set the duration for the randomized test")
+	repoPathPrefix    = flag.String("repo-path-prefix", "", "Point the robustness tests at this path prefix")
 )

 func TestMain(m *testing.M) {
+	flag.Parse()
+
 	var err error

 	eng, err = engine.NewEngine("")
-	if err != nil {
-		log.Println("skipping robustness tests:", err)
-
-		if err == kopiarunner.ErrExeVariableNotSet || errors.Is(err, fio.ErrEnvNotSet) {
-			os.Exit(0)
-		}

+	switch {
+	case err == kopiarunner.ErrExeVariableNotSet || errors.Is(err, fio.ErrEnvNotSet):
+		fmt.Println("Skipping robustness tests if KOPIA_EXE is not set")
+		os.Exit(0)
+	case err != nil:
+		fmt.Printf("error on engine creation: %s\n", err.Error())
 		os.Exit(1)
 	}

-	switch {
-	case os.Getenv(engine.S3BucketNameEnvKey) != "":
-		eng.InitS3(context.Background(), s3DataPath, s3MetadataPath)
-	default:
-		eng.InitFilesystem(context.Background(), fsDataPath, fsMetadataPath)
+	dataRepoPath := path.Join(*repoPathPrefix, dataSubPath)
+	metadataRepoPath := path.Join(*repoPathPrefix, metadataSubPath)
+
+	// Try to reconcile metadata if it is out of sync with the repo state
+	eng.Checker.RecoveryMode = true
+
+	// Initialize the engine, connecting it to the repositories
+	err = eng.Init(context.Background(), dataRepoPath, metadataRepoPath)
+	if err != nil {
+		// Clean the temporary dirs from the file system, don't write out the
+		// metadata, in case there was an issue loading it
+		eng.CleanComponents()
+		fmt.Printf("error initializing engine for S3: %s\n", err.Error())
+		os.Exit(1)
+	}
+
+	// Restore a random snapshot into the data directory
+	_, err = eng.ExecAction(engine.RestoreIntoDataDirectoryActionKey, nil)
+	if err != nil && err != engine.ErrNoOp {
+		eng.Cleanup()
+		fmt.Printf("error restoring into the data directory: %s\n", err.Error())
+		os.Exit(1)
 	}

 	result := m.Run()

 	err = eng.Cleanup()
 	if err != nil {
-		panic(err)
+		log.Printf("error cleaning up the engine: %s\n", err.Error())
+		os.Exit(2)
 	}

 	os.Exit(result)
--- a/tests/robustness/robustness_test/robustness_test.go
+++ b/tests/robustness/robustness_test/robustness_test.go
@@ -3,77 +3,112 @@
 package robustness

 import (
-	"context"
 	"fmt"
-	"io/ioutil"
-	"math/rand"
-	"path/filepath"
+	"strconv"
 	"testing"
+	"time"

+	"github.com/kopia/kopia/tests/robustness/engine"
 	"github.com/kopia/kopia/tests/testenv"
-	"github.com/kopia/kopia/tests/tools/fio"
 )

 func TestManySmallFiles(t *testing.T) {
-	fileSize := int64(4096)
-	numFiles := 100
+	fileSize := 4096
+	numFiles := 10000

-	fioOpt := fio.Options{}.WithFileSize(fileSize).WithNumFiles(numFiles).WithBlockSize(4096)
+	fileWriteOpts := map[string]string{
+		engine.MaxDirDepthField:         strconv.Itoa(1),
+		engine.MaxFileSizeField:         strconv.Itoa(fileSize),
+		engine.MinFileSizeField:         strconv.Itoa(fileSize),
+		engine.MaxNumFilesPerWriteField: strconv.Itoa(numFiles),
+		engine.MinNumFilesPerWriteField: strconv.Itoa(numFiles),
+	}

-	err := eng.FileWriter.WriteFiles("", fioOpt)
+	_, err := eng.ExecAction(engine.WriteRandomFilesActionKey, fileWriteOpts)
 	testenv.AssertNoError(t, err)

-	ctx := context.TODO()
-	snapID, err := eng.Checker.TakeSnapshot(ctx, eng.FileWriter.LocalDataDir)
+	snapOut, err := eng.ExecAction(engine.SnapshotRootDirActionKey, nil)
 	testenv.AssertNoError(t, err)

-	output, err := ioutil.TempFile("", t.Name())
-	testenv.AssertNoError(t, err)
-
-	defer output.Close()
-
-	err = eng.Checker.RestoreSnapshot(ctx, snapID, output)
+	_, err = eng.ExecAction(engine.RestoreSnapshotActionKey, snapOut)
 	testenv.AssertNoError(t, err)
 }

-func TestModifyWorkload(t *testing.T) {
-	const (
-		numSnapshots = 10
-		numDirs      = 10
-		maxOpsPerMod = 5
-	)
+func TestOneLargeFile(t *testing.T) {
+	fileSize := 40 * 1024 * 1024
+	numFiles := 1

-	numFiles := 10
-	writeSize := int64(65536 * numFiles)
-	fioOpt := fio.Options{}.
-		WithDedupePercentage(35).
-		WithRandRepeat(false).
-		WithBlockSize(4096).
-		WithFileSize(writeSize).
-		WithNumFiles(numFiles)
+	fileWriteOpts := map[string]string{
+		engine.MaxDirDepthField:         strconv.Itoa(1),
+		engine.MaxFileSizeField:         strconv.Itoa(fileSize),
+		engine.MinFileSizeField:         strconv.Itoa(fileSize),
+		engine.MaxNumFilesPerWriteField: strconv.Itoa(numFiles),
+		engine.MinNumFilesPerWriteField: strconv.Itoa(numFiles),
+	}

-	var resultIDs []string
+	_, err := eng.ExecAction(engine.WriteRandomFilesActionKey, fileWriteOpts)
+	testenv.AssertNoError(t, err)

-	ctx := context.Background()
+	snapOut, err := eng.ExecAction(engine.SnapshotRootDirActionKey, nil)
+	testenv.AssertNoError(t, err)

-	for snapNum := 0; snapNum < numSnapshots; snapNum++ {
-		opsThisLoop := rand.Intn(maxOpsPerMod) + 1
-		for mod := 0; mod < opsThisLoop; mod++ {
-			dirIdxToMod := rand.Intn(numDirs)
-			writeToDir := filepath.Join(t.Name(), fmt.Sprintf("dir%d", dirIdxToMod))
+	_, err = eng.ExecAction(engine.RestoreSnapshotActionKey, snapOut)
+	testenv.AssertNoError(t, err)
+}

-			err := eng.FileWriter.WriteFiles(writeToDir, fioOpt)
-			testenv.AssertNoError(t, err)
+func TestManySmallFilesAcrossDirecoryTree(t *testing.T) {
+	// TODO: Test takes too long - need to address performance issues with fio writes
+	fileSize := 4096
+	numFiles := 1000
+	filesPerWrite := 10
+	actionRepeats := numFiles / filesPerWrite
+
+	fileWriteOpts := map[string]string{
+		engine.MaxDirDepthField:         strconv.Itoa(15),
+		engine.MaxFileSizeField:         strconv.Itoa(fileSize),
+		engine.MinFileSizeField:         strconv.Itoa(fileSize),
+		engine.MaxNumFilesPerWriteField: strconv.Itoa(filesPerWrite),
+		engine.MinNumFilesPerWriteField: strconv.Itoa(filesPerWrite),
+		engine.ActionRepeaterField:      strconv.Itoa(actionRepeats),
+	}
+
+	_, err := eng.ExecAction(engine.WriteRandomFilesActionKey, fileWriteOpts)
+	testenv.AssertNoError(t, err)
+
+	snapOut, err := eng.ExecAction(engine.SnapshotRootDirActionKey, nil)
+	testenv.AssertNoError(t, err)
+
+	_, err = eng.ExecAction(engine.RestoreSnapshotActionKey, snapOut)
+	testenv.AssertNoError(t, err)
+}
+
+func TestRandomizedSmall(t *testing.T) {
+	st := time.Now()
+
+	opts := engine.ActionOpts{
+		engine.ActionControlActionKey: map[string]string{
+			string(engine.SnapshotRootDirActionKey):          strconv.Itoa(2),
+			string(engine.RestoreSnapshotActionKey):          strconv.Itoa(2),
+			string(engine.DeleteRandomSnapshotActionKey):     strconv.Itoa(1),
+			string(engine.WriteRandomFilesActionKey):         strconv.Itoa(8),
+			string(engine.DeleteRandomSubdirectoryActionKey): strconv.Itoa(1),
+		},
+		engine.WriteRandomFilesActionKey: map[string]string{
+			engine.IOLimitPerWriteAction:    fmt.Sprintf("%d", 512*1024*1024),
+			engine.MaxNumFilesPerWriteField: strconv.Itoa(100),
+			engine.MaxFileSizeField:         strconv.Itoa(64 * 1024 * 1024),
+			engine.MaxDirDepthField:         strconv.Itoa(3),
+		},
+	}
+
+	for time.Since(st) <= *randomizedTestDur {
+		err := eng.RandomAction(opts)
+		if err == engine.ErrNoOp {
+			t.Log("Random action resulted in no-op")
+
+			err = nil
 		}

-		snapID, err := eng.Checker.TakeSnapshot(ctx, eng.FileWriter.LocalDataDir)
-		testenv.AssertNoError(t, err)
-
-		resultIDs = append(resultIDs, snapID)
-	}
-
-	for _, snapID := range resultIDs {
-		err := eng.Checker.RestoreSnapshot(ctx, snapID, nil)
 		testenv.AssertNoError(t, err)
 	}
 }
--- a/tests/robustness/snap/snap.go
+++ b/tests/robustness/snap/snap.go
@@ -10,6 +10,7 @@ type Snapshotter interface {
 	CreateSnapshot(sourceDir string) (snapID string, err error)
 	RestoreSnapshot(snapID string, restoreDir string) error
 	DeleteSnapshot(snapID string) error
+	RunGC() error
 	ListSnapshots() ([]string, error)
 	Run(args ...string) (stdout, stderr string, err error)
 }
--- a/tests/robustness/snapmeta/index.go
+++ b/tests/robustness/snapmeta/index.go
@@ -0,0 +1,36 @@
+package snapmeta
+
+// Index is a map of index name to the keys associated
+// with that index name.
+type Index map[string]map[string]struct{}
+
+// AddToIndex adds a key to the index of the given name.
+func (idx Index) AddToIndex(key, indexName string) {
+	if _, ok := idx[indexName]; !ok {
+		idx[indexName] = make(map[string]struct{})
+	}
+
+	idx[indexName][key] = struct{}{}
+}
+
+// RemoveFromIndex removes a key from the index of the given name.
+func (idx Index) RemoveFromIndex(key, indexName string) {
+	if _, ok := idx[indexName]; !ok {
+		return
+	}
+
+	delete(idx[indexName], key)
+}
+
+// GetKeys returns the list of keys associated with the given index name.
+func (idx Index) GetKeys(indexName string) (ret []string) {
+	if _, ok := idx[indexName]; !ok {
+		return ret
+	}
+
+	for k := range idx[indexName] {
+		ret = append(ret, k)
+	}
+
+	return ret
+}
--- a/tests/robustness/snapmeta/index_test.go
+++ b/tests/robustness/snapmeta/index_test.go
@@ -0,0 +1,32 @@
+package snapmeta
+
+import (
+	"testing"
+)
+
+func TestIndex(t *testing.T) {
+	idx := Index{}
+
+	const (
+		snapshotIndexName = "snapshotIndex"
+		snapIDKey         = "snapID1"
+	)
+
+	idx.AddToIndex(snapIDKey, snapshotIndexName)
+
+	keys := idx.GetKeys(snapshotIndexName)
+	if got, want := len(keys), 1; got != want {
+		t.Fatalf("expected %v keys but got %v", want, got)
+	}
+
+	if got, want := keys[0], snapIDKey; got != want {
+		t.Fatalf("expected %v but got %v", want, got)
+	}
+
+	idx.RemoveFromIndex(snapIDKey, snapshotIndexName)
+
+	keys = idx.GetKeys(snapshotIndexName)
+	if got, want := len(keys), 0; got != want {
+		t.Fatalf("expected %v keys but got %v", want, got)
+	}
+}
--- a/tests/robustness/snapmeta/kopia_meta.go
+++ b/tests/robustness/snapmeta/kopia_meta.go
@@ -16,6 +16,7 @@
 type kopiaMetadata struct {
 	*Simple
 	localMetadataDir string
+	persistenceDir   string
 	snap             *kopiarunner.KopiaSnapshotter
 }

@@ -31,8 +32,14 @@ func New(baseDir string) (Persister, error) {
 		return nil, err
 	}

+	persistenceDir, err := ioutil.TempDir(localDir, "kopia-persistence-root")
+	if err != nil {
+		return nil, err
+	}
+
 	return &kopiaMetadata{
 		localMetadataDir: localDir,
+		persistenceDir:   persistenceDir,
 		Simple:           NewSimple(),
 		snap:             snap,
 	}, nil
@@ -61,6 +68,8 @@ func (store *kopiaMetadata) ConnectOrCreateFilesystem(path string) error {
 	return store.snap.ConnectOrCreateFilesystem(path)
 }

+const metadataStoreFileName = "metadata-store-latest"
+
 // LoadMetadata implements the DataPersister interface, restores the latest
 // snapshot from the kopia repository and decodes its contents, populating
 // its metadata on the snapshots residing in the target test repository.
@@ -76,21 +85,21 @@ func (store *kopiaMetadata) LoadMetadata() error {

 	lastSnapID := snapIDs[len(snapIDs)-1]

-	restorePath := filepath.Join(store.localMetadataDir, "kopia-metadata-latest")
-
-	err = store.snap.RestoreSnapshot(lastSnapID, restorePath)
+	err = store.snap.RestoreSnapshot(lastSnapID, store.persistenceDir)
 	if err != nil {
 		return err
 	}

-	defer os.Remove(restorePath) //nolint:errcheck
+	metadataPath := filepath.Join(store.persistenceDir, metadataStoreFileName)

-	f, err := os.Open(restorePath) //nolint:gosec
+	defer os.Remove(metadataPath) //nolint:errcheck
+
+	f, err := os.Open(metadataPath) //nolint:gosec
 	if err != nil {
 		return err
 	}

-	err = json.NewDecoder(f).Decode(&(store.Simple.m))
+	err = json.NewDecoder(f).Decode(&(store.Simple))
 	if err != nil {
 		return err
 	}
@@ -98,26 +107,34 @@ func (store *kopiaMetadata) LoadMetadata() error {
 	return nil
 }

+// GetPersistDir returns the path to the directory that will be persisted
+// as a snapshot to the kopia repository.
+func (store *kopiaMetadata) GetPersistDir() string {
+	return store.persistenceDir
+}
+
 // FlushMetadata implements the DataPersister interface, flushing the local
 // metadata on the target test repo's snapshots to the metadata Kopia repository
 // as a snapshot create.
 func (store *kopiaMetadata) FlushMetadata() error {
-	f, err := ioutil.TempFile(store.localMetadataDir, "kopia-metadata-")
+	metadataPath := filepath.Join(store.persistenceDir, metadataStoreFileName)
+
+	f, err := os.Create(metadataPath)
 	if err != nil {
 		return err
 	}

 	defer func() {
-		f.Close()           //nolint:errcheck
-		os.Remove(f.Name()) //nolint:errcheck
+		f.Close()               //nolint:errcheck
+		os.Remove(metadataPath) //nolint:errcheck
 	}()

-	err = json.NewEncoder(f).Encode(store.Simple.m)
+	err = json.NewEncoder(f).Encode(store.Simple)
 	if err != nil {
 		return err
 	}

-	_, err = store.snap.CreateSnapshot(f.Name())
+	_, err = store.snap.CreateSnapshot(store.persistenceDir)
 	if err != nil {
 		return err
 	}
--- a/tests/robustness/snapmeta/simple.go
+++ b/tests/robustness/snapmeta/simple.go
@@ -1,6 +1,12 @@
 package snapmeta

-import "sync"
+import (
+	"errors"
+	"sync"
+)
+
+// ErrKeyNotFound is returned when the store can't find the key provided.
+var ErrKeyNotFound = errors.New("key not found")

 var _ Store = &Simple{}

@@ -8,15 +14,17 @@
 // snapshot metadata as a byte slice in a map in memory.
 // A Simple should not be copied.
 type Simple struct {
-	m  map[string][]byte
-	mu sync.Mutex
+	Data map[string][]byte `json:"data"`
+	Idx  Index             `json:"idx"`
+	mu   sync.Mutex
 }

 // NewSimple instantiates a new Simple snapstore and
 // returns its pointer.
 func NewSimple() *Simple {
 	return &Simple{
-		m: make(map[string][]byte),
+		Data: make(map[string][]byte),
+		Idx:  Index(make(map[string]map[string]struct{})),
 	}
 }

@@ -28,7 +36,7 @@ func (s *Simple) Store(key string, val []byte) error {
 	s.mu.Lock()
 	defer s.mu.Unlock()

-	s.m[key] = buf
+	s.Data[key] = buf

 	return nil
 }
@@ -38,14 +46,14 @@ func (s *Simple) Load(key string) ([]byte, error) {
 	s.mu.Lock()
 	defer s.mu.Unlock()

-	if buf, found := s.m[key]; found {
+	if buf, found := s.Data[key]; found {
 		retBuf := make([]byte, len(buf))
 		_ = copy(retBuf, buf)

 		return retBuf, nil
 	}

-	return nil, nil
+	return nil, ErrKeyNotFound
 }

 // Delete implements the Storer interface Delete method.
@@ -53,19 +61,29 @@ func (s *Simple) Delete(key string) {
 	s.mu.Lock()
 	defer s.mu.Unlock()

-	delete(s.m, key)
+	delete(s.Data, key)
 }

-// GetKeys implements the Storer interface GetKeys method.
-func (s *Simple) GetKeys() []string {
+// AddToIndex implements the Storer interface AddToIndex method.
+func (s *Simple) AddToIndex(key, indexName string) {
 	s.mu.Lock()
 	defer s.mu.Unlock()

-	ret := make([]string, 0, len(s.m))
-
-	for k := range s.m {
-		ret = append(ret, k)
-	}
-
-	return ret
+	s.Idx.AddToIndex(key, indexName)
+}
+
+// RemoveFromIndex implements the Indexer interface RemoveFromIndex method.
+func (s *Simple) RemoveFromIndex(key, indexName string) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	s.Idx.RemoveFromIndex(key, indexName)
+}
+
+// GetKeys implements the Indexer interface GetKeys method.
+func (s *Simple) GetKeys(indexName string) []string {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	return s.Idx.GetKeys(indexName)
 }
--- a/tests/robustness/snapmeta/simple_test.go
+++ b/tests/robustness/snapmeta/simple_test.go
@@ -0,0 +1,25 @@
+package snapmeta
+
+import (
+	"testing"
+)
+
+func TestSimpleWithIndex(t *testing.T) {
+	simple := NewSimple()
+
+	storeKey := "key-to-store"
+	data := []byte("some stored data")
+	simple.Store(storeKey, data)
+
+	idxName := "index-name"
+	simple.AddToIndex(storeKey, idxName)
+
+	idxKeys := simple.GetKeys(idxName)
+	if got, want := len(idxKeys), 1; got != want {
+		t.Fatalf("expected %v keys but got %v", want, got)
+	}
+
+	if got, want := idxKeys[0], storeKey; got != want {
+		t.Fatalf("expected key %v but got %v", want, got)
+	}
+}
--- a/tests/robustness/snapmeta/snapmeta.go
+++ b/tests/robustness/snapmeta/snapmeta.go
@@ -10,7 +10,14 @@ type Store interface {
 	Store(key string, val []byte) error
 	Load(key string) ([]byte, error)
 	Delete(key string)
-	GetKeys() []string
+	Indexer
+}
+
+// Indexer describes methods surrounding categorization of keys via a named index.
+type Indexer interface {
+	AddToIndex(key, indexName string)
+	RemoveFromIndex(key, indexName string)
+	GetKeys(indexName string) (ret []string)
 }

 // Persister describes the ability to flush metadata
@@ -20,5 +27,6 @@ type Persister interface {
 	snap.RepoManager
 	LoadMetadata() error
 	FlushMetadata() error
+	GetPersistDir() string
 	Cleanup()
 }
--- a/tests/tools/fswalker/fswalker.go
+++ b/tests/tools/fswalker/fswalker.go
@@ -38,6 +38,8 @@ func NewWalkCompare() *WalkCompare {
 			filterFileTimeDiffs,
 			isRootDirectoryRename,
 			dirSizeMightBeOffByBlockSizeMultiple,
+			ignoreGIDIfZero,
+			ignoreUIDIfZero,
 		},
 	}
 }
@@ -204,6 +206,28 @@ func filterFileTimeDiffs(str string, mod fswalker.ActionData) bool {
 	return strings.Contains(str, "ctime:") || strings.Contains(str, "atime:") || strings.Contains(str, "mtime:")
 }

+func ignoreGIDIfZero(str string, mod fswalker.ActionData) bool {
+	if !strings.Contains(str, "gid:") {
+		return false
+	}
+
+	beforeGID := mod.Before.Stat.Gid
+	afterGID := mod.After.Stat.Gid
+
+	return beforeGID != afterGID && beforeGID == 0
+}
+
+func ignoreUIDIfZero(str string, mod fswalker.ActionData) bool {
+	if !strings.Contains(str, "uid:") {
+		return false
+	}
+
+	beforeUID := mod.Before.Stat.Uid
+	afterUID := mod.After.Stat.Uid
+
+	return beforeUID != afterUID && beforeUID == 0
+}
+
 func validateReport(report *fswalker.Report) error {
 	if len(report.Modified) > 0 {
 		return errors.New("files were modified")