CBT Reset in v9

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Re: CBT Reset in v9

Veeam Logoby Pat490 » Wed Feb 10, 2016 6:59 pm 1 person likes this post

the script worked great for me. you can do multiple VMs at once or single VM every time you run the script. I guess it depends on the amount of VMs that you have in your environment. But cbt reset has to be done!
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Re: CBT Reset in v9

Veeam Logoby stewsie » Thu Feb 11, 2016 9:36 am

I am not a PowerCLI expert so please bear with me.

I have run the script against one VM and although it appears to work I see some red text with the following.

Proceed with resetting CBT for all 1 listed VMs? [Y/n] : y
Code: Select all
-------------------------------------------------------------------------------
Processing server
===============================================================================
Reconfiguring server to set SCSI0:0.ctkEnabled FALSE
Reconfiguring server to set SCSI0:1.ctkEnabled FALSE
Reconfiguring server to set ctkEnabled FALSE
Creating snapshot
[color=#FF0000]New-Snapshot : 11/02/2016 09:09:22    New-Snapshot        An item with the same key has already been added.
At C:\Files\Scripts\CBTReset\ResetCBT.ps1:149 char:33
+     Get-VM -name $vm | New-Snapshot <<<<  -Name Snapshotcbt -Description "snapshot for cbt reset" | Out-Null
    + CategoryInfo          : NotSpecified: (:) [New-Snapshot], VimException
    + FullyQualifiedErrorId : Core_BaseCmdlet_UnknownError,VMware.VimAutomation.ViCore.Cmdlets.Commands.NewSnapshot[/color]

Deleting all snapshots on server
Reconfiguring server to set SCSI0:0.ctkEnabled TRUE
Reconfiguring server to set SCSI0:1.ctkEnabled TRUE
Reconfiguring server to set ctkEnabled TRUE
===============================================================================
CBT has been reset for  server
-------------------------------------------------------------------------------

-------------------------------------------------------------------------------
Press any key to exit...


The snapshot process appears to complete in 2 seconds. I need to understand why the snapshot process errors in PowerCLI and if CBT Reset has actually worked.

Thanks
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[MERGED] : reset cbt during upgrade 8 to 9 ?

Veeam Logoby geraldb » Tue Feb 23, 2016 8:16 am

Hi,

in the veeam b&r upgrade document (version 9) there is a point with:
Reset CBT for all VMs in the environment. For more information, refer to Veeam support article KB1940.
this point is listed after the upgrade is done ..
but the linked KB-entry is just for Version: 5.x, 6.x, 7.x, 8.x
https://www.veeam.com/kb1940

so do we have to do it ?

in this KB-entry it says also:
The following commands can be used to reset CBT for all VMs where it is presently enabled.
(Run these one line at a time after connecting to the vCenter Server via VMware PowerCLI.)

we only have standalone hosts without vcenter server .. is this a problem ?
ESXi hosts are version 5.1.0

best regards
Gerald
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Re: reset cbt during upgrade 8 to 9 ?

Veeam Logoby geraldb » Tue Feb 23, 2016 8:36 am

P.S.: if we have never extended any vmdk disk we don't have to reset CBT ?
Am I right ?
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Re: reset cbt during upgrade 8 to 9 ?

Veeam Logoby geraldb » Tue Feb 23, 2016 10:20 am

ok .. we have done the reset ob CBT already on all VMs ..

just for my understanding ..
After reseting CBT .. there should be full backups done from veeam of all VMs ?
replicas should also be "fully recreated" because CBT is reseted ?
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Re: reset cbt during upgrade 8 to 9 ?

Veeam Logoby PTide » Tue Feb 23, 2016 10:30 am

Hi,

After reseting CBT .. there should be full backups done from veeam of all VMs ?
Resetting CBT will cause Veeam to read the whole VM disks. However if you suspect that your backup chain might have been corrupted then yes - you should do an active Full.

replicas should also be "fully recreated" because CBT is reseted ?
No, they should not. After CBT reset the whole VM disk will be read in order to find what blocks has chenged since last backup. The same applies to replication - the same amount of data to be transferred however initial virtual disk read might take significantly longer.

Please see the thread you've been merged to, escpecially this post and let us know if any questions persist.

Thank you.
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Re: CBT Reset in v9

Veeam Logoby geraldb » Tue Feb 23, 2016 10:39 am

ok, thx!
sorry, I didn't saw that there is an existing thread for this
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Re: CBT Reset in v9

Veeam Logoby Gostev » Tue Feb 23, 2016 9:24 pm

Actually it is the same thread as you posted your question in, just the first page of it ;)
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Re: CBT Reset in v9

Veeam Logoby lukejf » Wed Jul 06, 2016 7:53 am

Hi Guys, I have ran the script in this post across some of our 5.5 hosts as come across an issue in a test restore. How do you determine if the CBT reset? The next veeam job doesn't seem to indicate any differences.

Edit
Looks like the read data in the veeam job before and after the reset indicates it has worked. Am i correct that the lastest version of veeam will now pickup HD changes and reset the CBT as required?
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Re: CBT Reset in v9

Veeam Logoby Vitaliy S. » Wed Jul 06, 2016 12:09 pm

Veeam backup server itself does not reset CBT data for the VMs you protect. If you did this manually and the entire virtual disk was read, then all subsequent runs will be using CBT data again.
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Re: CBT Reset in v9

Veeam Logoby lukejf » Thu Jul 07, 2016 5:02 am

Vitaliy S. wrote:Veeam backup server itself does not reset CBT data for the VMs you protect. If you did this manually and the entire virtual disk was read, then all subsequent runs will be using CBT data again.

Reading the KB it indicates that future disk resizing will be detected by veeam and will reset the CBT. Is this information not accurate - See below.
Veeam Backup and Replication 8 has a built-in solution for this issue. Veeam Backup & Replication resets CBT for any resized VMware disk to prevent corruption.
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Re: CBT Reset in v9

Veeam Logoby Vitaliy S. » Thu Jul 07, 2016 11:44 am

Yes, that quote is correct, I was just saying that issues discussed in this topic are not about disk resizing, but rather about ESXi updates that affect CBT data. This is not tracked by a built-in solution of the Veeam backup server.
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Re: CBT Reset in v9

Veeam Logoby Peejay62 » Mon Nov 28, 2016 9:33 am

At last, finally I will be able to upgrade to V9.. Just to talk about this CBT reset again. We are running V8.0.0.2084 en VMware 6.0 u2. Isn't it a viable option to reset cbt prior to upgrading to V9? I do not feel like cbt-resetting 200TB worth of VMs.
As it isn't a Veeam issue anyway and V8 seems to be handling any cbt bug this could be a convenient way for me to go to V9. I do some phased CBT resets in the coming weeks, after all completed I then upgrade to V9.
That aside, we have done numerous restores and surebackups and verifications the last year and we haven't encountered any cbt issues till today.

Thanks, Peter
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Re: CBT Reset in v9

Veeam Logoby m.novelli » Mon Nov 28, 2016 9:39 am 1 person likes this post

I run the "Mass reset cbt.ps" script that you can find here https://www.veeam.com/kb1940 at every vSphere upgrade, I've never had issues out of dozens of customers
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Re: CBT Reset in v9

Veeam Logoby Gostev » Mon Nov 28, 2016 5:32 pm

m.novelli wrote:I run the "Mass reset cbt.ps" script that you can find here https://www.veeam.com/kb1940 at every vSphere upgrade

I totally agree with this approach, especially if the environment size is not very large (otherwise, you can do this in portions).
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