juicedata/juicefs · error

scan slices: %s

Error message

scan slices: %s

What it means

Wraps the non-zero meta.Status returned by Meta.ScanSlices when `juicefs gc` (external-sort mode) iterates all slices, including pending ones, in the metadata engine. The scan aborts on context cancellation, metadata engine errors, or callback errors, and the status code is formatted into this message.

Source

Thrown at cmd/gc_external.go:152

		metaSliceSpin.Increment()
		var state uint8
		switch ino {
		case 0:
			state = gcStatePending
		case 1:
			state = gcStateTrash
		default:
			state = gcStateUsed
		}
		select {
		case output <- gcMetaRecord{sliceID: s.Id, size: s.Size, state: state}:
			return nil
		case <-c.Done():
			return c.Err()
		}
	})
	if st != 0 {
		return errors.Errorf("scan slices: %s", st)
	}
	return nil
}

func scanGcObjectRecords(ctx context.Context, blob object.ObjectStorage, output chan<- gcObjectRecord, threads int, hashPrefix bool, maxMtime time.Time, prefixSpin, objScanSpin *utils.Bar, skipped *utils.DoubleSpinner) error {
	return scanGcChunkObjects(ctx, blob, threads, hashPrefix, prefixSpin, func(obj object.Object) error {
		select {
		case <-ctx.Done():
			return ctx.Err()
		default:
		}
		var ok bool
		obj, ok = filterGcObject(ctx, blob, obj, maxMtime, objScanSpin, skipped)
		if !ok {
			return nil
		}
		record, ok := parseGcObjectRecord(obj)
		if !ok {

View on GitHub (pinned to c9a67b23e8)

Solutions

1. Decode the status code in the message and check connectivity/health of the metadata engine (e.g. `redis-cli ping`, `mysql -e 'select 1'`)
2. Re-run the gc command; transient engine/network errors often resolve on retry
3. Look for a sibling 'produce meta records'/'produce object records' error in the log that caused context cancellation
4. Reduce gc concurrency/threads if the engine is timing out under scan load

Example fix

// before
juicefs gc --threads 64 redis://prod-redis:6379/1   # engine times out
// after
juicefs gc --threads 8 redis://prod-redis:6379/1    # lighter scan load

if err := pingMetadataEngine(metaURL); err != nil { return fmt.Errorf("metadata engine unreachable: %w", err) } // e.g. redis-cli PING, MySQL SELECT 1

if err := gcExternalSort(...); err != nil {
	if isTransient(err) { /* retry with backoff */ }
	log.Printf("gc scan failed: %v — check metadata engine health", err)
}

When it happens

Trigger: Calling `juicefs gc` when the metadata engine (Redis/SQL/KV) returns an error while iterating slices; the meta.Context is cancelled (e.g. another goroutine in the errgroup failed or the process was interrupted); a scan callback returns an error (e.g. sorter input failure).

Common situations: Redis/MySQL connection drops mid-gc; gc interrupted by Ctrl-C; one concurrent producer (object scan) fails causing meta context cancellation via errgroup; metadata backend timeouts under heavy load.

Understand the failure class

Background: Database query failed: Internal Server Error 500s wrapping SQL, Prisma, and connection failures — what to check first — this error's family across 16 libraries.

Related errors

• scan trash slices: %s
• produce meta records: %s
• database %s is used by volume %s
• load setting: %s
• new session: %s

AI-assisted analysis of juicedata/juicefs@c9a67b23e8 (2026-09-06). Data as JSON: /api/errors/1a09bc15d1f4a7f9. Report an issue: GitHub.