What happens when you backup a VM outside the normal job?

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What happens when you backup a VM outside the normal job?

Veeam Logoby cparker4486 » Tue Feb 28, 2017 8:47 pm

Hello,

Does backing up a VM outside its regular job impact what's backed up in the regular job?

Asked another way, is CBT calculated per VM between runs of the same job or each time a VM is backed up by a job?
-- Chris
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Re: What happens when you backup a VM outside the normal job

Veeam Logoby Andreas Neufert » Tue Feb 28, 2017 9:35 pm

Any CBT works that way that it will increase the internal flag for changed storage areas by 1 when you create a new snapshot. It doesn´t matter if this was done manually or by different backup vendors.

What a Veeam job knows is that his lates state was a specific number, let´s say 42323. If someone now started other backup jobs or created manual snapshots the new number is maybe 42333. Now Veeam knows what it needs to backup everything that is newer than 42323 at next run.
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Re: What happens when you backup a VM outside the normal job

Veeam Logoby cparker4486 » Tue Feb 28, 2017 9:49 pm

Oh I see. I was under the impression that CBT was a flag of true/false and that it was reset when a backup was taken.

Instead, you're saying that each backup of a VM, for the same job, is a diff between the old and new state of that VM. CBT facilitates a fast method to perform that diff (as opposed to the slow method of a block-by-block comparison.)

Do I have it right?
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Re: What happens when you backup a VM outside the normal job

Veeam Logoby Andreas Neufert » Tue Feb 28, 2017 9:52 pm 1 person likes this post

Correct we know the old state, look into CBT what has changed and read only those block areas. Multiple backups or 3rd party backups do not affect this.
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