Configure QCBM Archive and Split-ZIP Settings

The archive settings in a QCBM Backup Profile control how file data is packaged before the verified Recovery Package is built. For most sites, Auto / Recommended is the right starting point because QCBM can choose between a normal ZIP, Split ZIP, or TAR.GZ based on available PHP support and the site's size.

Customize these settings only when you have a clear hosting, storage, transfer, or recovery requirement.

Open Archive and Split Strategy

  1. Go to Components > QC Backup Manager > Profiles.
  2. Edit the Profile.
  3. Find Archive and Split Strategy.
  4. Choose the Archive strategy.
  5. If Split ZIP may be used, review the Split size.
  6. Save the Profile and test it with a real verified Backup Set.

Archive Strategy Choices

QCBM 1.5.13 provides five Profile choices:

  • Auto / Recommended — uses ZIP when PHP ZipArchive is available, selecting Split ZIP when QCBM's size scan indicates a large archive; if ZIP is unavailable but PHP PharData is available, Auto falls back to TAR.GZ.
  • ZIP archive — creates a single ZIP for file-containing backups.
  • Split ZIP archive — builds and verifies the complete ZIP, then writes it into numbered split parts.
  • TAR archive — requires PHP PharData.
  • TAR.GZ archive — requires PHP PharData and produces a compressed TAR-style archive.

Database-only backups do not need a site-file archive in the same way Files Only and Full backups do.

How Auto Decides Between ZIP and Split ZIP

When ZipArchive is available, Auto examines the included file set using the Profile's exclusions. If the scan is large enough to reach the selected split threshold—or the bounded readiness scan has to stop early because the site is large—QCBM can choose Split ZIP. Otherwise it uses a normal ZIP.

The Status page's Large Site Readiness information is useful before changing this policy manually. A large site can need substantially more temporary disk space than the final Recovery Package alone.

Choose a Split Size

The Split size choices are Auto / Recommended, 100 MB, 250 MB, 500 MB, 1 GB, and Custom. Auto currently uses a 250 MB split target. A custom value can be from 25 MB through 5120 MB.

Smaller parts can be easier to transfer through restrictive hosting or remote-storage environments, but they create more files that must remain together. Larger parts reduce the part count but may be more difficult to transfer or handle on constrained systems.

What Happens During Split ZIP Creation

QCBM does not stream unrelated fragments directly into the final Backup Set. It first creates and verifies the complete ZIP, then writes split parts in bounded byte ranges. Each part is recorded and checksummed, and QCBM verifies that the combined split size matches the finalized source archive.

Because the complete ZIP and split output can coexist during staging, Split ZIP can temporarily require more disk space. QCBM's preflight accounts for this and also checks whether split staging and final storage share the same filesystem.

Do Not Choose a Split Size Based on One Large Source File

A source file larger than the selected split size can still be included. QCBM builds the archive first and splits the finalized archive afterward. The split threshold is therefore about the output archive parts, not a maximum size for individual Joomla source files.

Verify a Custom Archive Policy

After changing the strategy or split size, create a controlled Backup Set with that Profile. In Backup History, confirm that the Backup Set completes and verifies and that the canonical Recovery Package is available. For Split ZIP, confirm all expected parts are present and healthy.

If a forced ZIP strategy fails because ZipArchive is unavailable, or a TAR strategy fails because PharData is unavailable, either enable the required PHP capability or return the Profile to Auto / Recommended.

When to Leave Auto Enabled

Leave Auto enabled when you do not have a measured reason to force a format. The automatic path is designed to adapt to the PHP archive support and size characteristics QCBM can actually see on the current site.

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.