High Stun time during snapshot removal on VVOL

SAN transport is not supported for backup or restore of virtual machines residing on VVol datastores. To overcome this limitation nowadays many organization prefer to use VMware hot add backup.

How Hot add backup works?

Backup software runs in a virtual appliance, it takes a snapshot and create a linked clone of the target virtual machine, then attach and read the linked clone’s virtual disks for backup. This involves a SCSI Hot Add on the ESXi host where the target VM and backup proxy are running. Virtual disks of the linked clone are Hot Added to the backup proxy. The target virtual machine continues to run during the backup.

Using Host add for vVol based VM:  

Hot add backups work fine for vvol based VMs when backup Proxy VM and Production VMs are running on the same ESXi host. But when Proxy VM and Production VMs are hosted on two different ESXi hosts production VMs experiences long stun time.


Snapshot delete operation can not be completed due to volume bind on another ESXi host. Snapshot delete operation completes as soon as the unbinding process completes.


Keeping Proxy VM and Production VM on the same ESXi host will avoid unnecessary long stun time during snapshot deletion.

Leave a comment