I have a VMware ESXi 5 environment running on Fujitsu BX922S2 blade servers, connecting to a Fujitsu DX90 SAN.
I've had no problem with RAID5 volumes, but RAID10 volumes (for MSSQL) are exhibiting ridiculous write latency - up over 1000 ms at times, and never lower than about 30 ms. These latency figures are being measured in VMware, using the Performance tab for the SQL server concerned, changing to Advanced, then switching to Datastore view.
The DBA noticed this, and wrote a quick script to continuously create a 1GB file on the server.
Migrating the SQL logs drive to a RAID 5 volume on the same SAN shows no perceptible write latency.
Can anyone point to anything obvious I've configured incorrectly that would cause this?