topic Re: va7410 optimum queue depth for luns in Disk Enclosures

va7410 optimum queue depth for luns

Charles McCary — Thu, 25 Sep 2008 18:18:41 GMT

Group,

I have a va7410 with 67 luns ranging in size from 10gb to 100gb.

This array is connected to a hard partitioned rp7420 (effectively two systems).

All disks are at the default queue depth for HPUX 11.11, is there some way to figure if I need to change the scsi queue depth and if so to what?

I know this relates to the number of luns, number of host ports (in this case 4), etc...but I'm not sure about the calculation or if I need to apply whatever I come up with to all disks.

Further info, running several different databases on the two systems (oracle).

thanks,

c

Re: va7410 optimum queue depth for luns

skris — Fri, 26 Sep 2008 17:17:11 GMT

Hi Charles,
Normally the QFT is set to 750.If you have been seeing QFull messages then you could consider altering them:

Here is a formula that yields Best results:

2 or 3*(#disks in RG)/(#ports in RG)

PS: There isn't a mandatory rule as such.

For HP-UX, you need to have PHKL_29047 to avoid host performance issues when the host gets the Queue Full message from the array.

Cheers!
Shiva

Re: va7410 optimum queue depth for luns

Charles McCary — Fri, 26 Sep 2008 17:54:18 GMT

We're not getting any errors, but I'm just concerned that I'm not getting the best perf out of the array.