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albertwt
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What to do with VM with the CBT feature disabled ?

Post by albertwt » Oct 31, 2014 4:55 am

Hi,

I've noticed that there are at least 25-30 % of my VMs does not have the CBT feature enabled when running the following Powershell script:

Code: Select all

https://github.com/alanrenouf/vCheck-vSphere
So I wonder if I should do something about it or does Veeam can automatically set the feature to be on ?
or is there any reason as to why the specific VM on the list above must not use CBT ?

Any kind of help and suggestion would be greatly appreciated.

Thanks,
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VladV
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Re: What to do with VM with the CBT feature disabled ?

Post by VladV » Oct 31, 2014 6:36 am 1 person likes this post

CBT is disabled by default and gets enabled automatically when the VM is processed by Veeam and the option "Enable CBT for all protected VMs automatically" is selected in the Backup or Replication job.

CBT is used to enable the backup software do a real incremental run by mapping the modified blocks in a timeline, si it will read only those blocks on incremental runs.

As to whether or not those specific VMs should have CBT disabled is only up to you, but I can't see how CBT would have a negative impact on them.

albertwt
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Re: What to do with VM with the CBT feature disabled ?

Post by albertwt » Oct 31, 2014 6:39 am

VladV wrote:CBT is disabled by default and gets enabled automatically when the VM is processed by Veeam and the option "Enable CBT for all protected VMs automatically" is selected in the Backup or Replication job.

CBT is used to enable the backup software do a real incremental run by mapping the modified blocks in a timeline, si it will read only those blocks on incremental runs.

As to whether or not those specific VMs should have CBT disabled is only up to you, but I can't see how CBT would have a negative impact on them.

So yeah, that's what I thought before. I'm not sure as to why those VMs is not automatically set CBT enabled by Veeam ?
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VladV
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Re: What to do with VM with the CBT feature disabled ?

Post by VladV » Oct 31, 2014 6:40 am 1 person likes this post

Are they included in a backup or replication job?

albertwt
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Re: What to do with VM with the CBT feature disabled ?

Post by albertwt » Oct 31, 2014 6:42 am

VladV wrote:Are they included in a backup or replication job?
yes they are.
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VladV
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Re: What to do with VM with the CBT feature disabled ?

Post by VladV » Oct 31, 2014 8:04 am 1 person likes this post

Are they proxies used by VBR? I noticed that those VMs aren't processed using CBT and no warning or errors are logged.

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Re: What to do with VM with the CBT feature disabled ?

Post by albertwt » Oct 31, 2014 9:06 am

VladV wrote:Are they proxies used by VBR? I noticed that those VMs aren't processed using CBT and no warning or errors are logged.
No those VMs are not VBR proxies.
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Vitaliy S.
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Re: What to do with VM with the CBT feature disabled ?

Post by Vitaliy S. » Oct 31, 2014 9:51 am 1 person likes this post

Do you have this checkbox turned on " Enable changed block tracking for all processed VMs"? See our online helpcenter web page for more info > http://helpcenter.veeam.com/backup/70/v ... ghtsub=CBT

joergr
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Re: What to do with VM with the CBT feature disabled ?

Post by joergr » Oct 31, 2014 9:55 am 1 person likes this post

Hmmmmm.....COULD it be your VM Hardware Version is less than 7? That would explain it.

CBT needs minimum HW7. If B+R finds a hardware version less, it will simply not use cbt. Very simple ;-)

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Re: What to do with VM with the CBT feature disabled ?

Post by albertwt » Oct 31, 2014 2:22 pm

joergr wrote:Hmmmmm.....COULD it be your VM Hardware Version is less than 7? That would explain it.

CBT needs minimum HW7. If B+R finds a hardware version less, it will simply not use cbt. Very simple ;-)

Is it v8 or 9 that is not automatically enabled ?
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joergr
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Re: What to do with VM with the CBT feature disabled ?

Post by joergr » Oct 31, 2014 2:27 pm 1 person likes this post

Albert,

please read http://kb.vmware.com/selfservice/micros ... Id=1020128
especially "The virtual machine owning the disks to be tracked must be hardware version 7 or later".

Best regards,
Joerg

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Re: What to do with VM with the CBT feature disabled ?

Post by albertwt » Nov 01, 2014 1:23 am

Cool, thanks !
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