Host-based backup of VMware vSphere VMs.
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Differences in how reverse incremental backups work

Post by randomizedname »

I have two vmware ESXi servers in different locations. Both of them are backed up using Veeam Backup & Replication to NAS devices. Backup mode is set to reverse incremental on both, but it works completely different:

1st server:


2nd server:


The amount of processed data is similar but look at the backup duration and the amount of read data. How this is possible?
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Re: Differences in how reverse incremental backups work

Post by Mildur » 1 person likes this post


Read data depends on the blocks veeam needs to read from the source esxi. It has no dependency on the reverse incremental type.
If you have CBT enabled, read data only contains blocks which are changed between the backups.
If CBT data is not available for a VM or it was reseted (for example on an active full backup), veeam needs to read the entire disk and not only changed blocks. This will take much longer and read data will be higher.

I suggest to analyze your backup job session logs if CBT was used or not.

You can also open a case with our support. They will be able to tell you what was happening with the job and CBT feature.

Product Management Analyst @ Veeam Software
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