Host-based backup of Microsoft Hyper-V VMs.
Post Reply
jonhsykes
Influencer
Posts: 10
Liked: never
Joined: Dec 14, 2011 4:24 pm
Full Name: JS
Contact:

Discover which VMs/VHDs don't have CBT?

Post by jonhsykes »

Is there a way to discover VM replicas that don't have CBT through PowerShell script or some other mechanism?
jonhsykes
Influencer
Posts: 10
Liked: never
Joined: Dec 14, 2011 4:24 pm
Full Name: JS
Contact:

Re: Discover which VMs/VHDs don't have CBT?

Post by jonhsykes »

bump
Gostev
Chief Product Officer
Posts: 31460
Liked: 6648 times
Joined: Jan 01, 2006 1:01 am
Location: Baar, Switzerland
Contact:

Re: Discover which VMs/VHDs don't have CBT?

Post by Gostev »

For VMware or Hyper-V? Your question is confusing because CBT is a VMware thing (Hyper-V uses RCT), but VHD is a Hyper-V thing (VMware uses VMDK).
jonhsykes
Influencer
Posts: 10
Liked: never
Joined: Dec 14, 2011 4:24 pm
Full Name: JS
Contact:

Re: Discover which VMs/VHDs don't have CBT?

Post by jonhsykes »

Hyper-V 2012 R2. I know the files are stored on Hyper-V hosts, however it would be nice if there was a reporting mechanism inside of VEEAM to use for this scenario to report on the VMs that don't have CBT (ie wont use incremental replication for next replication cycle). It's helpful for large data center migrations
https://helpcenter.veeam.com/docs/backu ... tml?ver=95
vClintWyckoff
Veteran
Posts: 500
Liked: 109 times
Joined: Oct 27, 2012 1:22 am
Full Name: Clint Wyckoff
Location: Technical Evangelist
Contact:

Re: Discover which VMs/VHDs don't have CBT?

Post by vClintWyckoff » 1 person likes this post

Just to reiterate there is no native change block tracking in Hyper-V on 2012R2, so Veeam uses a filter driver that gets installed on the actual Hyper-V hosts to track the changes since the previous backup. In the rare cases where there is issues with either CBT on vSphere or in your case the filter driver on Hyper-V, VBR will read each block to determine whether or not its changed since the previous backup. So in any case you're left with an incremental backup.

As stated in the link you posted above...
CBT is enabled by default. You can disable it either at the host level or at the job level for troubleshooting purposes. Note that if you choose to run incremental jobs with CBT disabled, the backup window may increase dramatically, as Veeam Backup & Replication will read all VM data to detect what blocks have changed since the last job session.
However, as Anton mentioned RCT (Resilient Change Tracking) is available in Hyper-v 2016 making the filter driver no longer required. Hope this helps.
Post Reply

Who is online

Users browsing this forum: No registered users and 18 guests