nasbackup.sh: add optional backup compression via -c flag#12844
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jmsperu wants to merge 1 commit intoapache:4.20from
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nasbackup.sh: add optional backup compression via -c flag#12844jmsperu wants to merge 1 commit intoapache:4.20from
jmsperu wants to merge 1 commit intoapache:4.20from
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Add -c/--compress flag that produces compressed qcow2 backup files, reducing storage usage on the NAS backup target. For stopped VMs: passes -c to qemu-img convert directly. For running VMs: re-compresses push backup output with qemu-img convert -c after the backup job completes. Compression is off by default to preserve existing behavior and avoid increased CPU usage on hosts that don't need it. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Additional details and impacted files@@ Coverage Diff @@
## 4.20 #12844 +/- ##
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- Coverage 16.24% 4.15% -12.10%
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Files 5664 404 -5260
Lines 500463 32966 -467497
Branches 60779 5893 -54886
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- Hits 81308 1370 -79938
+ Misses 410059 31420 -378639
+ Partials 9096 176 -8920
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Pull request overview
Adds an optional -c/--compress flag to nasbackup.sh so NAS backups can be written as compressed qcow2 images (default remains uncompressed), reducing backup storage usage.
Changes:
- Introduces
-c/--compressCLI flag and wires it into the backup workflow. - For stopped VMs, conditionally adds
-ctoqemu-img convert. - For running VMs, performs a post-backup recompression pass over generated
.qcow2files.
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| for disk in $DISK_PATHS; do | ||
| volUuid="${disk##*/}" | ||
| qemu-img convert -O qcow2 $disk $dest/$name.$volUuid.qcow2 | tee -a "$logFile" | ||
| qemu-img convert $([[ "$COMPRESS" == "true" ]] && echo "-c") -O qcow2 $disk $dest/$name.$volUuid.qcow2 | tee -a "$logFile" |
| for img in "$dest"/*.qcow2; do | ||
| [[ -f "$img" ]] || continue | ||
| local tmp_img="${img}.tmp" | ||
| if qemu-img convert -c -O qcow2 "$img" "$tmp_img" 2>&1 | tee -a "$logFile"; then |
| [[ -f "$img" ]] || continue | ||
| local tmp_img="${img}.tmp" | ||
| if qemu-img convert -c -O qcow2 "$img" "$tmp_img" 2>&1 | tee -a "$logFile"; then | ||
| mv "$tmp_img" "$img" |
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Summary
-c/--compressflag to produce compressed qcow2 backup files, reducing NAS storage usage-ctoqemu-img convertdirectly (single pass, no extra I/O)qemu-img convert -cafter backup completesMotivation
NAS backup storage fills up quickly with large VM disks. qcow2 compression typically achieves 40-60% size reduction with minimal CPU overhead, extending backup retention without additional storage.
The
-cflag can be passed by the CloudStack agent when the admin enables compression in the backup repository settings, giving per-repository control.Test plan
-c— verify identical behavior to current-c— verify compressed qcow2 output (check withqemu-img info)-c— verify post-backup compression, smaller file sizes