What counters should I baseline before moving to a SAN?
for the last three weeks I was moving some of my servers off of direct attached storage(DAS) to a SAN. I have had success with all of them and enjoyed performance boost and flexiblity so far. However one of the servers suddenly start taking 2-3 times for maintenance jobs(backup and integrity check). This happened after they did SAN related maintenance on the backup array which theoretically should only affect the backup process. However integrity check is also taking very long time. The only thing i have on this instance running is maintenance jobs since this is a new server and the databases are getting upgraded to support an application upgrade so I dont have application/database performance baseline to compare it with....No configuration change is made regarding SQL SErver. What do you think should I check for troubleshooting(or tell the SAN team to check)? (Additional info about the environment: This particular instance is a win 2008 R2, SQL 2008 R2 Ent, 24GB RAM and all DATA(RAID5) log/tempdb/(RAID1) and backup are on separate arrays and the SAN is EMC CLARiiON) Also, most importantly, since I still have other servers which are currently in production that I have to move to the SAN, what counter should I check before moving as a baseline to compare performance? Thanks.
I/O per second. You need to check the through put of the disks. You need to make sure that you get equal or better iops on the new SAN. You can have the state of the art SAN but if the disk are not configured properly you are toast. How many spindles do your luns have? How is the cache configured on the SAN? There are tools out there SQL IO SIM that can generate loads for you to test. The documentation online is very helpful for benchmarking the systems. Also [Brent Ozar](
http://www.brentozar.com) has some great material on his blog.