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arcserve-KB : Agentless Backups - Full backups based on the types of disks

Last Update: 2016-11-23 11:41:39 UTC
Does UDP backup the full disk during a full Agentless Backup?


Agentless Backup on VMware Environment :


· If the Virtual Machine is on a VMFS Datastore, then during the full backup, only the used blocks are backed up.

The incrementals will backup only the changed blocks using the CBT feature provided by VMware

· If the Virtual Machine is on an NFS Datastore, then during the full backup, the used and unused blocks are backed up.

But the incrementals will backup only the changed blocks using the CBT feature provided by VMware

Agentless Backup on MS Hyper-V Environment :



The UDP agentless backup refers to the BAT (Block Allocation Table) for the backups

· For Fixed size VHD disk (Windows 2008/ 200R2), there is not BAT and hence the entire disk is backed up during the full backups. 
The incrementals will backup only the used blocks using the UDP CBT driver that is provided.

· For Fixed size VHDX disk (Windows 2012/ 2012 R2), all the blocks are marked as present in the BAT, and the entire disk is backed up during the full backups.

The incrementals will backup only the used blocks using the UDP CBT driver that is provided.

However this is some optimization provided for the full backups even though the entire disk is backed up. UDP writes only the non-zero blocks. 
By default, the logically unused blocks are with zero data and this is skipped from being backed up.

 
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