Differences in backup speed

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Differences in backup speed

Veeam Logoby tibrunet » Tue Dec 04, 2012 6:54 pm


I am seeing very different backup speed when backing up VMs from the same SAN / drives. For example, Exchange is the fastest @ 70 MB/s (constant across multiple runs) and other VMs as low as 38. I am using the Microsoft iSCSI hardware provider to do off-host backup on a separate network. The Veeam server carries all the roles (proxy, repository and DB). I am backing up only 1 VM at a time, when my SAN / Network / Servers are almost idle. The bottleneck is reported to be the target by 76%, but looking at Performance Monitor, it is not really busy.

What can cause backup speed to vary that much?

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Re: Differences in backup speed

Veeam Logoby Gostev » Tue Dec 04, 2012 8:00 pm


Considering that Exchange data compresses much better (as changed blocks mostly contain transaction logs), this results in less I/O load on your primary bottleneck (backup target) for each processed block, thus letting the overall backup process run faster for this VM (due to backup target not holding the processing as much).

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