Veeam 9 causes high write latency on SSD SAN

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Veeam 9 causes high write latency on SSD SAN

Veeam Logoby jdixon » Wed Nov 23, 2016 4:33 pm

We have a Hyper-V cluster with that is connected with 2-paths per server with 8GB fiber to a 3PAR 8200 (we have all 12Gbps SAS SSD). We noticed that for some reason we started getting alerts from Veeam One about very high write latencies when backups have occurred. Now when we were on our 3PAR 7200 10K SAS we didn't seem to have this problem.

We have narrowed it down to backups with Veeam causing this but we have not had a chance to narrow down if its the fiber channel HBA's that are the issue or the SAN itself. I find it hard to believe it the SAN because we cannot be pushing that amount of throughput because of the limitation with the fiber channel is less than the storage.

Has anyone else had this issue?
jdixon
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Re: Veeam 9 causes high write latency on SSD SAN

Veeam Logoby Gostev » Wed Nov 23, 2016 5:26 pm

As a first step, just enable Backup I/O Control to keep datastore latency at the desired level. Alternatively, you can simply reduce backup or repository proxy slots, as most likely you are just throwing too many concurrent tasks at your SAN.

Then, I recommend opening a case with HP, as I find it quite strange that SSD SAN struggles with our workload when HDD SAN does not (I'd expect the opposite).
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Re: Veeam 9 causes high write latency on SSD SAN

Veeam Logoby jdixon » Fri Dec 23, 2016 9:21 pm

I thought i fixed it by modifying the queue depth on the HBA on the servers.. but I still see high latency sometimes with 2x8Gbps paths. Haven't found how to limit the I/O control yet
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Re: Veeam 9 causes high write latency on SSD SAN

Veeam Logoby foggy » Tue Dec 27, 2016 3:18 pm

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