Bottleneck Confusion

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Re: Bottleneck Confusion

Veeam Logoby B.F. » Thu Sep 28, 2017 3:48 pm

OK, not trying to beat the horse but just trying to fully understand all the behind the scenes things that are going on.

I did another test where I have a test VM at the DR site. I then created a VMDK that is on the same iSCSI storage where the replica is dumped. The VMDK is mounted in my test VM as E:\

I ran 11 LAN Speed Test runs to E:\ using 1gb of data. I ran the test from the same Veeam server at the main site that the replication job runs from. The average Read is 63 MB/s and 46 MB/s Write. That is way more than what I'm seeing on Veeam. As I type this, there is a replication job running 87% complete and only getting 5MB/s processing rate.

Why such a large discrepancy?

Thanks
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Re: Bottleneck Confusion

Veeam Logoby foggy » Fri Sep 29, 2017 3:21 pm

Veeam B&R not just sequentially reads data from the source repository (like the test does), but needs to copy only changed blocks, which makes it (slower) random reads.
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Re: Bottleneck Confusion

Veeam Logoby B.F. » Fri Sep 29, 2017 7:35 pm

Ah, that makes sense. So if only changed blocks are figured out and read from the source, the writing of the replica to the destination should only need to write what was pulled from the source correct? There really shouldn't be much of a writing overhead then. Wouldn't the replica then be written in sequence?

Thanks!
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Re: Bottleneck Confusion

Veeam Logoby foggy » Sun Oct 01, 2017 9:07 pm

That's correct, but you should pay attention at your source, since it is the bottleneck in this case.
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