Very Low LUN Performance!

[Serverbaz90]

Hello, 

I have HP StoreVirtual VSA 2012 on both HP DL380 G8, G9, With two LUNs, LUN1 is 1.84TB (8x600GB 15K), LUN 2 is 1.34 TB (,  sometimes  we have disk latency and on our VMs disk we have Disk Queue Length, so I checked HP VSA performance in our pick time, so here is the result we have Disk Queue! 

I want to know, if I change VSA storage VM Memory from 4GB to 8GB, is it solved the problem? What is your recommendation? we have Microsoft SQL Server VMs that have has lot of Read and write.

[danevald]

Hi,

We unfortunately see this issue quite often on some or VSAs, quickest way to solve it is to look in VMware vCenter to see which VSA host has the highest Datastore Latency(Select Host, Select Performance tab, select Datastore view and look for the VSA datastores, one if usually a lot higher (500-5000ms compared to the normal 0-5) then reboot the VSA on that host. This wakes up the VSA again and will let it run as normal, until it happens again. We have this issue on multiple sites, but haven't been able to get to the bottom of what causes it. 

[BenLoveday]

Hi there,

I would suggest you add some SSD and enable Adaptive Optimisation. The small number of spindles you have suggests that you are going to hit the ceiling of your underlying disk performance regularly. 

I'm not sure of your RAID layout but even using RAID10 at best you will get 1000-1500 IOPS read off those 15K disks, and half that for write (assuming no RAID controller caching).

We use AO and it works pretty well. If you aren't licensed for AO you could create a dedicated SSD tier and move the heavy stuff to that. Just make sure you use some decent enterprise SAS/SATA SSD with at least 1 DWPD. You can probably calculate your required duty cycle from the CMC data you have.

Cheers,

Ben

[BenLoveday]

Just a comment for danevald about his high VSA latencies. We had exactly this issue and was killing our clusters. We ended up having HPE create a custom patch to disable LRO on our VSA's (this can't be changed by the customer) and our latencies are super low and stable now. Might be worth contacting support for something similar. If you only have a few VSA's (we have over 60) then they can apply the changes manually via a support call.

[Serverbaz90]

Thank you so much, Ben. Yeah AO is a good idea i think, but we have already buy 4TB License, so it's difficult to buy new license. I think we have to get new SSD drive and add it as new local drive and change our heavy stuff to that.