topic Re: SWAP SPACE in Operating System - HP-UX

SWAP SPACE

David Dangerfield_1 — Thu, 24 Sep 2009 13:05:57 GMT

I am trying to add swap. I was able to add some but needed to add more per the DBA request. Once I added the last swap needed and tried to do a swapon -a I get the following.

# swapon -a
Enabling device paging on /dev/vg00/swap.
swapon: /dev/vg00/swap is already enabled for paging.
Enabling device paging on /dev/vg00/lvol2.
swapon: /dev/vg00/lvol2 is already enabled for paging.
Enabling device paging on /dev/vg02/lvol_swap.
swapon: The kernel tunable parameter "swchunk" needs to be increased to add
paging on device /dev/vg02/lvol_swap.

I have done adjusted swchunk to max and it is showing that not using anything of it. what did i do wrong beside listen to DBA.

Re: SWAP SPACE

Sunny123_1 — Thu, 24 Sep 2009 13:21:13 GMT

Hi

How do you adjust swapchunk for that refer follow

Total_swap_that_can_be_configured
=maxswapchunks * swapchunk

If your system has following parmeters
maxswapchunks=4096
swchunk=2048

then

the total swap you can configure is 4096*2048 = 8388608 which is 8 GB.

If you want to add more swap, then calculate the maxswapchunks by the same forumula

However, the limit for maxswapchunks is 16384. If you need to go beyond that limit, then you will need to increase the swchunk size

Regards
Sunny

Re: SWAP SPACE

David Dangerfield_1 — Thu, 24 Sep 2009 13:32:29 GMT

I am in the kernel setting and don't see a maxswap of any kind. HP UX 11.23 is the OS i am running.

Re: SWAP SPACE

Hakki Aydin Ucar — Thu, 24 Sep 2009 13:41:49 GMT

After changed the kernel value ,did you reboot your system to update last value in kernel ?

Re: SWAP SPACE

David Dangerfield_1 — Thu, 24 Sep 2009 13:46:55 GMT

Yes sure did do that.

Re: SWAP SPACE

Sunny123_1 — Thu, 24 Sep 2009 13:59:32 GMT

Hi

Look for maxswapchunks.

Regards
Sunny

Re: SWAP SPACE

Hakki Aydin Ucar — Thu, 24 Sep 2009 14:15:38 GMT

I think it is for you: check this out;

http://docs.hp.com/en/B2355-60130/swchunk.5.html

Re: SWAP SPACE

David Dangerfield_1 — Thu, 24 Sep 2009 14:20:38 GMT

Not that neither. attached is a list of parms on this box.

Re: SWAP SPACE

Hakki Aydin Ucar — Thu, 24 Sep 2009 14:24:35 GMT

I think that there is NOT a maxswapchunks parameter any more for 11i version 2; check this post:

http://forums13.itrc.hp.com/service/forums/questionanswer.do?admit=109447627+1253805746626+28353475&threadId=1076814

Re: SWAP SPACE

Rita C Workman — Thu, 24 Sep 2009 14:30:35 GMT

Hi David,

maxswapchunks was obsoleted on 11.23.

Have you tried simply using 'SAM' to add your additional swapspace. You can still use it on version 11.23 (even 11.23IA). It's old and slow, but it does work.

Rgrds,
Rita

Re: SWAP SPACE

Don Morris_1 — Thu, 24 Sep 2009 17:03:47 GMT

Considering the max value of swchunk can get you to 1Tb on 11.23, we need more data.

What's the output from:

swapinfo -atm

kctune -v swchunk

?

How big is /dev/vg02/lvol_swap, anyway?

Are you under memory pressure?

Does dmesg show any messages about failure to add swap? (Usually there's a statement in the message buffer as to why the swap add failed).

Re: SWAP SPACE

David Dangerfield_1 — Thu, 24 Sep 2009 18:22:30 GMT

Problem is solved. never seen this happen before but it seems that after going to the building where this server is we had a drive bad which just so happen to be the drive we were trying to put the swap on even though it had a mirror drive once i replaced that drive and it rebuilt itself i was able to create the swap without any problems. who knows.

Re: SWAP SPACE

David Dangerfield_1 — Thu, 24 Sep 2009 18:23:56 GMT

THANKS