nasbackup.sh: add bandwidth throttle via -b flag#12846
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jmsperu wants to merge 1 commit intoapache:4.20from
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nasbackup.sh: add bandwidth throttle via -b flag#12846jmsperu wants to merge 1 commit intoapache:4.20from
jmsperu wants to merge 1 commit intoapache:4.20from
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Add -b/--bandwidth flag (MiB/s) to limit backup I/O impact on production workloads. For running VMs: uses virsh blockjob --bandwidth to throttle the QEMU push backup job per disk. For stopped VMs: uses qemu-img convert -r rate limit and ionice -c 3 (idle I/O class) to minimize impact on other VMs. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## 4.20 #12846 +/- ##
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Coverage 16.24% 16.24%
Complexity 13411 13411
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Files 5664 5664
Lines 500463 500463
Branches 60779 60779
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+ Hits 81308 81312 +4
+ Misses 410059 410058 -1
+ Partials 9096 9093 -3
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Pull request overview
Adds optional bandwidth throttling to the KVM NAS backup script to reduce backup I/O impact during running-VM and stopped-VM backups.
Changes:
- Introduces a
-b|--bandwidthCLI option and updates usage text accordingly. - Applies bandwidth limiting to running-VM backups via
virsh blockjob --bandwidth. - Applies bandwidth limiting to stopped-VM backups via
qemu-img convertrate limiting andionice.
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| for disk in $(virsh -c qemu:///system domblklist $VM --details 2>/dev/null | awk '/disk/{print$3}'); do | ||
| virsh -c qemu:///system blockjob $VM $disk --bandwidth "${BANDWIDTH}" 2>/dev/null || true | ||
| done | ||
| log -ne "Backup bandwidth limited to ${BANDWIDTH} MiB/s per disk for $VM" |
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| # Throttle backup bandwidth if requested (MiB/s per disk) | ||
| if [[ -n "$BANDWIDTH" ]]; then | ||
| for disk in $(virsh -c qemu:///system domblklist $VM --details 2>/dev/null | awk '/disk/{print$3}'); do | ||
| virsh -c qemu:///system blockjob $VM $disk --bandwidth "${BANDWIDTH}" 2>/dev/null || true | ||
| done |
| for disk in $DISK_PATHS; do | ||
| volUuid="${disk##*/}" | ||
| qemu-img convert -O qcow2 $disk $dest/$name.$volUuid.qcow2 | tee -a "$logFile" | ||
| ionice -c 3 qemu-img convert $([[ -n "$BANDWIDTH" ]] && echo "-r" "${BANDWIDTH}M") -O qcow2 $disk $dest/$name.$volUuid.qcow2 | tee -a "$logFile" |
| for disk in $DISK_PATHS; do | ||
| volUuid="${disk##*/}" | ||
| qemu-img convert -O qcow2 $disk $dest/$name.$volUuid.qcow2 | tee -a "$logFile" | ||
| ionice -c 3 qemu-img convert $([[ -n "$BANDWIDTH" ]] && echo "-r" "${BANDWIDTH}M") -O qcow2 $disk $dest/$name.$volUuid.qcow2 | tee -a "$logFile" |
Contributor
|
@jmsperu Please see #12848 (comment) |
jmsperu
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Mar 26, 2026
… integrity check Adds four optional features to NAS backup operations, configurable at zone scope via CloudStack global settings: - Compression (-c): qcow2 internal compression of backup files Config: nas.backup.compression.enabled (default: false) - LUKS Encryption (-e): encrypt backup files at rest using qemu-img Config: nas.backup.encryption.enabled (default: false) Config: nas.backup.encryption.passphrase (Secure category) - Bandwidth Throttle (-b): limit backup I/O bandwidth via virsh blockjob for running VMs or qemu-img -r for stopped VMs Config: nas.backup.bandwidth.limit.mbps (default: 0/unlimited) - Integrity Check (--verify): qemu-img check after backup creation Config: nas.backup.integrity.check (default: false) All features are disabled by default and fully backward compatible. Settings are read from zone-scoped ConfigKeys in NASBackupProvider, passed to the KVM agent via TakeBackupCommand details map, and translated to nasbackup.sh CLI flags in LibvirtTakeBackupCommandWrapper. Changes: - nasbackup.sh: add -c, -b, -e, --verify flags with encrypt_backup() and verify_backup() helper functions - TakeBackupCommand.java: add details map for passing config to agent - NASBackupProvider.java: add 5 ConfigKeys, populate command details - LibvirtTakeBackupCommandWrapper.java: extract details, build CLI args, handle passphrase temp file lifecycle Combines and supersedes PRs apache#12844, apache#12846, apache#12848, apache#12845
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Summary
-b/--bandwidthflag (MiB/s) to limit backup I/O impact on production workloadsvirsh blockjob --bandwidthper diskqemu-img convert -rrate limit +ionice -c 3(idle I/O class)Motivation
Backup jobs on shared storage can saturate I/O bandwidth and degrade performance for production VMs on the same host or NAS. This is especially problematic during business hours or when multiple VMs are being backed up concurrently.
The bandwidth limit can be passed by the CloudStack agent based on a global or per-repository setting, giving admins control over backup impact.
Test plan
-b— verify no throttling, identical to current behavior-b 50— verifyblockjob --bandwidthapplied, checkdomjobinfoshows throttled rate-b 50— verifyionice -c 3and-r 50Min process list