Here's a little background of my environment. I am running SQL Server 2008 R2 SP2 64-bit on a two-node Windows Server 2012 R2 cluster. The storage is an Equallogic group consisting of one PS6100XS (hybrid SSD/10k SAS hard drives in RAID 6 Accelerated) and two PS6000E arrays.
I have noticed that I get several messages in the SQL logs pertaining to "SQL Server has encountered ##### occurrence(s) of I/O requests taking longer than 15 seconds to complete on file [x:\TempDB Data\tempdbxx.xDF] in database [tempdb] (2). The OS file handle is 0x00000000000000E3C. The offset of the latest long I/O is: 0x000001159d0000." It only occurs when I execute an UPDATE STATISTICS WITH FULLSCAN on large tables.
The database used to be on PS6000XV (15k SAS drives) in RAID 10 with a PS6000E and PS61000E and the servers were Windows Server 2008 R2. There was no issue in that setup. I also only had six data files with T-1118 enabled.
I have opened a ticket with Dell Equallogic and they seem to think that it's not a SAN issue. I have added more tempdb data files from eight to 12 and enabled T-1118. I don't know if it matters, but all of the data files are 20GB each. I have disabled Delayed ACK and Nagle's Algorithm and it has helped a little.
Does anyone happen to know what the issue could be? Would I need to increase my tempdb data files to 16? I thought the issue is with the SAN...