topic Re: XP512 Disk I/O issues in Disk Enclosures

XP512 Disk I/O issues

Tom Stewart_2 — Thu, 27 Jul 2006 10:43:20 GMT

I am new to this system and have been informed that there is a large report job that runs on the system which is taking a lot longer to complete than it should. The issue seems to be disk I/O, while investigating I noticed that cache Lun is not initialised and am wondering if initialising this would improve disk I/O performance?

Thanks in advance

Re: XP512 Disk I/O issues

Chris Callihan_1 — Fri, 28 Jul 2006 09:12:26 GMT

cache lun is a licensed feature (costs extra if you have not already purchased). it allows you to lock an entire lun into the array's cache. but this would take cache that the array manages in the manner it feels would give best performance, but that probably would not even be an option, i will guess that the size of the luns being accessed for you report job are larger than the cache in the array to begin with. even if it wasn't, i would not recommend this approach (or at least have a LOT more information before i pursued that path)

Re: XP512 Disk I/O issues

Dave La Mar — Fri, 28 Jul 2006 18:19:47 GMT

Tom-
If you have Measureware installed, you can use metrics and adviser only to monitor your i/o.
Even without cacheing, you might be able to better balance access to the luns via the pvlinks at the o/s level.
It is entirely possible the response time is due to an imbalance in the pathing to luns involved.

Regards,

-dl

Re: XP512 Disk I/O issues

Tom Stewart_2 — Tue, 01 Aug 2006 09:07:42 GMT

Thanks for the replies,
It seems the problem is the application and the large volume of data the report job needs to access. As a precaution a HP engineer is coming to check the system to ensure there are no issues with the system.

Thanks