Azure VM restore issues

Hello Ojha, Akhilesh (CORP)Thank you for posting your query on Microsoft Q&A portal.

Backup performance - Below are the common scenarios can affect the total backup time

• Adding a new disk to a protected Azure VM: If a VM is undergoing incremental backup and a new disk is added, the backup time will increase. The total backup time might last more than 24 hours because of initial replication of the new disk, along with delta replication of existing disks.
• Fragmented disks: Backup operations are faster when disk changes are contiguous. If changes are spread out and fragmented across a disk, backup will be slower.
• Disk churn: If protected disks that are undergoing incremental backup have a daily churn of more than 200 GB, backup can take a long time (more than eight hours) to complete.
• Backup versions: The latest version of Backup (known as the Instant Restore version) uses a more optimized process than checksum comparison for identifying changes. But if you're using Instant Restore and have deleted a backup snapshot, the backup switches to checksum comparison. In this case, the backup operation will exceed 24 hours (or fail).

Restore performance - Below are the common scenarios can affect the total restore time

• The total restore time depends on the Input/output operations per second (IOPS) and the throughput of the storage account.
• The total restore time can be affected if the target storage account is loaded with other application read and write operations. To improve restore operation, select a storage account that isn't loaded with other application data.

If your backup takes more than 12 hours or restore takes more than 6 hours, we suggest following these practices when you are configuring VM backups.

• Modify the default schedule times that are set in a policy. For example, if the default time in the policy is 12:00 AM, increment the timing by several minutes so that resources are optimally used.
• If you're restoring VMs from a single vault, we highly recommend that you use different general-purpose v2 storage accounts to ensure that the target storage account doesn't get throttled. For example, each VM must have a different storage account. For example, if 10 VMs are restored, use 10 different storage accounts.
• For backup of VMs that are using premium storage with Instant Restore, we recommend allocating 50% free space of the total allocated storage space, which is required only for the first backup. The 50% free space isn't a requirement for backups after the first backup is complete
• The limit on the number of disks per storage account is relative to how heavily the disks are being accessed by applications that are running on an infrastructure as a service (IaaS) VM. As a general practice, if 5 to 10 disks or more are present on a single storage account, balance the load by moving some disks to separate storage accounts.
• To restore VMs with managed disks using PowerShell, provide the additional parameter TargetResourceGroupName to specify the resource group to which managed disks will be restored Learn more here.

Reference: https://learn.microsoft.com/en-us/azure/backup/backup-azure-vms-troubleshoot#backup-or-restore-takes-time

If you are still facing issues, then please let me know the below details:

1. What type of VM are you trying to restore (Windows, Linux)?
2. Are you using the Azure portal, PowerShell, or some other method to initiate the restore?
3. Have you seen any specific error messages in the logs or on the Azure portal?
4. Can you confirm if you are trying to restore to the same region and subscription?
5. Are there any specific custom configurations or extensions attached to the VM that may cause the restore process?

Thanks,

Suchitra.