Needed your guidance to fix one of the performance issue where the writes are slow.
Some of the information:
SQL Server 2008R2.
OLTP environment.
32GB RAM.
16 Disks Raid 10.
Write latency on some of the db files is over 700 ms (virtual file stats dmv).
Over all DISK (not just file) latency in peak hours (perfmon) goes frequently to 200 ms.
Reads are pretty quick (below 30ms) in comparison to writes.
Writes in the log file are pretty quick (below 10ms) in comparison to writes to the data files.
I don’t see a huge buffer pool utilization (below 20 most of the times even during the peak hours) so I feel there is not a lot of activity which the server processes.
This is a pure OLTP environment which has 60% select and 40% DML (inserts, updates, deletes).
When there are more DMLs particularly the inserts as the new orders are accepted by the application, the database shows a lot of slowness and user complain that they are not able to generate the order sometime.
I feel the application has a design issue causing page splits as I found the same using fn_dblog and the perfmon counter page splits/sec.
I am then planning to move the fill factor all the way to 70% instead of 90% currently we have as the server default.
I know will impact the selects but I feel selects are not causing much of the issues.
We are also planning to add and create separate RAID disk groups for log, tempdb, data files and also move the largest (busiest) database to its own filegroup.
Apart from page splits and creating separate disk groups, do you guys see any other thing that I may consider for fixing this high writes latency issue.