Azure vm backup snapshot taking much longer than usual via recovery vault

Hi Mark Pearson,

Thank you for sharing the backup job history.

Looking at the timings, the main change is in the Take Snapshot step. It used to finish in about 8–9 minutes, but the last two backups took over 4 hours. The Transfer data to vault step hasn't grown; it was actually shorter in the last two runs. I also noticed that Validate Backup took about 15 minutes in the latest job, compared with 30 seconds before.

So, the extra time is mainly being spent while the VM snapshot is being created, not in the Recovery Services vault. During this step, Azure Backup works with the VM (and with Volume Shadow Copy Service, or VSS, on Windows) to capture a consistent point-in-time copy before any data moves to the vault.

A few quick questions to help narrow this down:

1. Is this a Windows or a Linux VM?
2. Did anything change on this VM about two weeks ago? For example: a change to the backup policy, a new or resized disk, a VM size change, new software such as SQL Server, Windows updates, or antivirus changes.
3. Could you share the Job IDs in private message of one slow backup and one normal backup?

Please check the below during the backup window (for a Windows VM):

1. CPU and memory: consistently high usage can delay the snapshot.
2. Disk activity (IOPS and latency): heavy disk activity can make VSS snapshots take much longer.
3. VSS writers: run vssadmin`` ``list`` ``writers from an elevated Command Prompt. All writers should show State: Stable and Last error: No error.
4. Event Viewer: check the Application and System logs around the backup time for VSS, VolSnap or disk-related errors.
5. VM Agent and backup extension: make sure the Windows Azure Guest Agent service is running in services.msc. In the Azure portal, go to VM>Settings>Extensions+applications and confirm the VMSnapshot extension shows Provisioning succeeded.
6. Other backup or snapshot activity: make sure no other backup tool or SQL native backup is taking a VSS snapshot at the same time.
7. Antivirus: if antivirus software was recently installed or updated, check that it isn't scanning or blocking the Azure Backup extension.

Please run one on-demand backup during a quiet period and watch CPU, memory and disk latency while it runs.

• If the snapshot step drops back to about 10 minutes, the delay is most likely caused by workload during your scheduled backup window. Moving the backup schedule to a quieter time should help.
• If it still takes several hours while the VM is idle and the VSS writers and backup extension look healthy, please send us the Job IDs and the results of the checks above, and we'll look into the snapshot operation further.

Please let us know once you've had a chance to run these checks.

Microsoft Reference Documents:

• About Azure VM backup
• Troubleshoot Azure Backup agent/extension and snapshot issues
• Troubleshoot backup errors with Azure VMs

Best regards,
Mohammad Saif