Hi
Being a newbie on NetApp there might be some obvious answer to the following question, so bare with me. We have most our stuff running on vmware and nfs, but we still have two SQL Clusters running iscsi (though planned for virtualization later this year - that's another story)
I'm migrating a SQL Server 2008 R2 Cluster running on Windows 2008 R1 (latest patch level) from Equallogic iscsi to NetApp iscsi. The migration itself went without any problem (failing the current drives, repairing them by pointing to a NetApp iscsi lun, bring them online and copy the data - slow and safe). After the migration was completed, I wanted to make sure that everything was working (including multipathing), so I copied a large file to a mounted lun - no problem each nic was loaded approx. 20% as expected. Then I tried read, here I should have the same nic load, but it was between 1-2%. I checked against the Equallogic box and it read the file with the expected approx. 20%. Since I was short on time before I had to initiate a fallback, I googled a bit and came across an article about fragmentation within WAFL. I did a reallocate measure, which came out with a 3, which isn't that bad. But I forced a reallocate on one of the luns, but it didn't improve the read performance. I noticed also a high latency seen in NetApp OnCommand System Manager 2.0 on iscsi ranging in the 200-300 ms, but don't have anymore than that. It's a production system so I can't try everything and next maintenance day is feb 17th. Oh, and there are no snapshots on the volume. Dedub is however enabled (large amounts of unchanged data in our SQL) and it's all SAS drives.
Do any of you have valuable input to how to approach this read performance problem - assuming it can be solved to a competing level?
Funny footnote - we replaced the Equallogic with the Netapp because of the high latency we saw ranging from 20ms to 2000ms (mostly in the 20-200ms) and until now I've only seen a latency below 10ms on our NetApp.
Cheers
Anders