Performance Issues

[HMUSER]

We have recently got our SAN up and running with no problems what so ever. We moved all the files on to the SAN and it seemed to be working very well.

However recently users have noticed a big delay in getting access to files from our SAN.

Has anyone got any ideas why this is doing this and whether they have an idea of where to check first

[bryan_hadzik]

Start with the performance monitor. Look for latency. Anything over 10-15 should be a concern. Look at total IOPS.  What is your drive type/number of modules/what type?

[HMUSER]

Most of the IOPS are between 0 and 10 with the average of 4.

We are running SAS 6Gb drives between 2 Arrays a total of 16 disks.

[oikjn]

IO Latency is the key number...  hopefully that is under 10.

Watch que depth...  that should be less than or equal to 2 times the number of 15k drives you have or 1.5 times the number of 10k drives or simply the number of 7.2k drives.

Watch the IOS of each VSA...  they should be able to do ~200 per 15k drive installed or I think 50-100 (can't remember) per 7.2k drive.

Watch VSA CPU usage....  make sure you aren't pegged at 100%

If any of those numbers are frequently above those ranges, its a sign that your drives are over saturated.

[Ryan Nelson_3]

Kinda of tangential to the actual post, but oikjn's got me wondering how one would have an impact on latency? 

Amiright that latency will be a function of internal system operation? Or at most, if flow control and the switches are working optimally, there isn't much else that can be tweaked?