Azure Recovery Vault Backup is failing for SQL VMs

Question

We are using Azure Recovery Vault Service for taking Azure VMs backup. Most of the VMs backup successfully. But a few VMs [SQL servers] backups are failing with the error message:

Could not copy the snapshot of the virtual machine, due to insufficient free space in the storage account. Ensure that storage account has free space equivalent to the data present on the premium storage disks attached to the virtual machine.

We have verified the premium storage account in which the VMs are created ; storage account size seems to be less than 35 TB only and having VHD counts less than 34.

Answer 1

Azure VM backups create a duplicate copy of the VM in the storage account of the disks being backed up. This means if you schedule all your backups at the same time, you can only use 17.5TB of space in a premium storage account.

One way to address this is to stagger the backups so they all don’t run at the same time. Another option is to spread your VMs out across multiple storage accounts.

The best option, though, is probably to switch to managed disks so you don't have to deal with storage account limitations.