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larry
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Full Name: Larry Walker
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Question With CBT Disabled how does Veeam work

Post by larry » Nov 23, 2015 8:00 pm

Question with CBT disabled and all blocks being read is this also verifying if any error could be in my backup chain ( since last full ) ? If a backup became corrupt from media failure while just sitting there will this get detected if part of the current chain? I now do weekly full backups just in case but if backing up without CBT verifying from the last full I would like to switch to once a month fulls. With 300-500meg reads seeing if I should leave change block off after the VMware 6 fix if it provides any extra protection. A with VMware 6 track record with CBT I am a little gun shy. Is there a way to disable CBT just one day a week?

P.Tide
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Re: Question With CBT Disabled how does Veeam work

Post by P.Tide » Nov 24, 2015 8:37 am

Hi,

Please see the article:
During backup, Veeam Backup & Replication <...>scans through the VM image and calculates a checksum for every data block.
<...>
When incremental backup is run, Veeam Backup & Replication opens all backup files in the chain of previous full and incremental backups, reads metadata from these files and compares it with checksums calculated for a VM in its current state. If a match is found (which means the block already exists in the backup), the corresponding block is filtered out.
This basically means that if any block in the backup file gets corrupted the next job run will not detect that the blocks are different since checksum is compared to checksum from meta.
Is there a way to disable CBT just one day a week?
Yes you can do that with PowerShell scripting.

Thank you.

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