Virtual Machine Backup Caused Multiple Map Disk Region

Multiple “Map disk region” tasks kept showing up in the vSphere Client for a virtual machine after I started a backup job in the Backup Exec.

A new Map disk region task appeared almost every second and was kind of “scary” until I confirmed that the virtual machine is running fine.

As pointed out by the KB Article The Map Disk Region task appears repeatedly in VirtualCenter after using VMware Consolidated Backup, this happens when the disk is severely fragmented.  Having a previous snapshot can also cause the disk to be considerably fragmented. 

I kind of suspect that it is caused by previous snapshot so I stopped the backup job which remove the current snapshot.  I went to the Snapshot Manager and there was indeed a snapshot created by previous backup job.  I deleted the snapshot and ran the backup job again without a single Map disk region task appearing.