topic Device Swap in Operating System - HP-UX

Device Swap

Khairul Azman Parnot — Wed, 19 Nov 2008 07:23:26 GMT

Hi,
Im having HPUX B.11.23 ia64. Curretly my swap usage as below;
swapinfo -tam
Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 1024 1024 0 100% 0 - 1 /dev/vg00/lvol2
dev 19456 10866 8590 56% 0 - 1 /dev/vg00/lvol9
reserve - 8590 -8590
memory 32635 24886 7749 76%
total 53115 45366 7749 85% - 0 -

>vmstat 1 5
procs memory page faults cpu
r b w avm free re at pi po fr de sr in sy cs us sy id
4 8 0 5556228 56682 5 1 10 10 0 0 185 10935 82881 4238 20 4 77
4 8 0 5556228 56639 3 0 3 0 0 0 0 18315 134461 8316 41 4 55
4 8 0 5556228 56635 2 0 3 0 0 0 0 19007 147557 8710 31 5 64
9 6 0 5699354 55840 11 0 23 0 0 0 0 20197 155564 9512 31 9 60
9 6 0 5699354 312270 20 0 26 0 0 0 0 19598 149815 9304 34 10 56

Does my swap need to be increase? currently we have performance issues and one of the thing that I look into is the device swap usage. Need expert help on this. Thanks.

Re: Device Swap

Steven E. Protter — Wed, 19 Nov 2008 07:39:56 GMT

Shalom,

No your swap does not need to increase.

Your system memory needs to increase.

Your system is under memory pressure, though its not paging heavily, your system is short of memory.

Adding swap might help prevent out of memory errors, but in the end, this will slow your system down.

Time to look into an increase in system memory. I'd look to add 2 gb or more.

For more perf data:
http://www.hpux.ws/?p=6

SEP

Re: Device Swap

Johnson Punniyalingam — Wed, 19 Nov 2008 08:09:25 GMT

Hi ,

swap space looks ..ok,

adding more pshyical memory will boot your performance,

Thanks,
Johnson

Re: Device Swap

Khairul Azman Parnot — Wed, 19 Nov 2008 08:51:03 GMT

Thanks everyone... look like need to propose this to management :), maybe take couple months before I can get new memory :)

Steven E. Protter,
I run the system.perf.sh, it show nothing, anything i do wrongly?

Re: Device Swap

Venkatesh BL — Wed, 19 Nov 2008 09:00:51 GMT

What kind of perf issues are you facing? If upgrading RAM is going to take time, you could increase swap for now.