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- Full Name: Jeff Nevins
I've seen some threads about CBT not working because of snapshots and that causing backup jobs to process the full hard drive...but in my case it seems like CBT actually IS working.
The problem started just under a week ago - for full backups of VMs our VMWare ESX 5.1U1 server, Veeam (located on a different physical server - eg using Network Backup) is processing and reading the entire drive capacity of the source VMs. This applies to all VMs on the source server.
The backup log looks something like this (for each VM):
Hard Disk 1 (100.0 GB) 99.3GB read at 52MB/s [CBT]
A week ago, a similar full backup read (for the same source VM):
Hard Disk 1 (100G.0 GB) 15.1 GB read at 39MB/s [CBT]
Needless to say, this is a huge problem, as full backups now take 12+ hours. How can I go about troubleshooting this?
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- Full Name: Kevin Clarke
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- Veeam Software
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- Full Name: Alexander Fogelson
That's true, in cases where there is at least one existing snapshot, CBT cannot be enabled on the VM. However, if CBT has been enabled prior to creating a snapshot, Veeam B&R will be able to successfully utilize CBT.JeffN825 wrote:I've seen some threads about CBT not working because of snapshots and that causing backup jobs to process the full hard drive...
It is enabled for this VM, however returns a huge amount of changed blocks for some reason. Is there anything that could cause huge amount of changes inside your VMs (defragmentation or antivirus scan for example)?JeffN825 wrote:but in my case it seems like CBT actually IS working.
That said, in some rare cases CBT data can get corrupt and trying to reset CBT could be the first step in addressing this issue.
Btw, what about incremental runs? Do you observe such behavior on full job runs only? Then the cause could be in dirty virtual disk data blocks belonging to the deleted files.
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