Understand QCBM Staged and Resumable Backup Processing

QCBM does not assume that one PHP request or one open browser connection can complete a large Joomla backup. Manual and scheduled Backup Sets are stored as persistent jobs and advanced through bounded worker checkpoints.

This design lets QCBM save progress between requests, continue the same Backup Set, and separate a browser interruption from an actual backup failure.

Why QCBM Uses Bounded Workers

Large Joomla sites can exceed normal request timeouts while dumping the database, scanning files, building an archive, hashing large files, splitting output, generating manifests, or building the Recovery Package. Trying to do all of that in one request makes success depend too heavily on PHP execution limits, proxy timeouts, and the administrator's browser connection.

QCBM instead performs a limited amount of work, records a checkpoint, and lets another worker request continue from that saved state.

What QCBM Persists

The persistent job records the Backup Set it belongs to, the current phase, progress, the saved payload needed for later work, and checkpoint information. Depending on the backup type, saved work can include database dump chunks, file-inventory checkpoints, archive progress, split-part progress, verification information, and Recovery Package state.

QCBM also writes live progress information for the administrator interface without making that display data responsible for the integrity of the backup itself.

Typical Processing Stages

A Full Backup can pass through stages such as:

  • preflight and Backup Set creation;
  • database structure/data/object checkpoints and SQL dump assembly;
  • bounded file inventory and metadata capture;
  • archive creation and archive verification;
  • Split ZIP preparation, copy, and verification when applicable;
  • backup-part checksums and manifest creation;
  • canonical Recovery Package creation and verification;
  • optional automatic export;
  • final completion.

Database Only and Files Only runs use the relevant subset of those stages.

A Browser Interruption Is Not Automatically a Failed Backup

If the browser loses its connection, the important question is the saved job state—not whether the progress window disappeared. QCBM can recognize an unfinished persistent manual Backup Set and resume that same saved job instead of automatically creating a duplicate.

Before clicking Create Manual Backup again, reopen QCBM and inspect the active backup controls and Backup History. If QCBM still has an active or resumable job, continue that job.

How Background Continuation Works

QCBM installs a dedicated QC Backup Manager Backup Continuation Joomla Scheduled Task. The installer normally creates it on a one-minute interval. It can advance queued/running persistent manual or scheduled jobs through another bounded checkpoint and can automatically resume a postponed job when its saved resume time arrives.

The per-job worker lock prevents a scheduler worker and an administrator browser worker from advancing the same job concurrently.

Pause, Postpone, and Cancel Preserve Safe State

Pause and Postpone change the saved persistent-job state rather than requiring you to kill PHP processes or delete files manually. Resume reacquires the QCBM backup-create operation lock and continues from the saved checkpoint. Cancel changes the job to a cancelling state and finalizes cancellation at a safe checkpoint.

Use those controls instead of editing QCBM database rows or deleting a working directory while a job is active.

Completion Still Requires Verification

Resumability protects the processing workflow, but a resumable job is not yet a recovery point. Treat the Backup Set as dependable only after QCBM reaches completion and verification and the canonical Recovery Package is available.

If a job fails, use its recorded failure phase and message to diagnose the actual stage. Do not infer the cause from whichever browser request happened to be visible when the failure surfaced.

What to Check When Progress Looks Stuck

  1. Open the active backup progress view and note the current activity and last progress time.
  2. Check whether the job is running, queued, paused, postponed, cancelling, complete, failed, or cancelled.
  3. Confirm the Backup Continuation Scheduled Task is enabled and healthy if background continuation is expected.
  4. Review Backup History and the recorded failure information before retrying.
  5. Do not start another Backup Set while the existing persistent job still owns the workflow.

Community Discussion

Want to compare workflows, share practical tips, or discuss how you use this QCBM feature? Visit the QC Backup Manager Community. For private support, bug reports, account-specific issues, or feature requests, use the QuantaCade support system.