topic swap_memory in Operating System - HP-UX

swap_memory

Indrajit_1 — Tue, 07 Feb 2006 14:24:33 GMT

Hi all;

What is the maximum "maxswapchunks" i can increase in kernel parameter on 9000/800/rp8420. The Physical mem is 45gb. My current swap memory is 46gb. i need to increase to 88gb.Please help me.

Cheers
Indrajit

Re: swap_memory

Luk Vandenbussche — Tue, 07 Feb 2006 14:32:37 GMT

Hi,

The maximum kernel parameter for maxswapchunks is 16384.

See also

http://www5.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000080025377

Re: swap_memory

James R. Ferguson — Tue, 07 Feb 2006 14:34:17 GMT

Hi:

The 'maxswapchunks' maximum value is 16384 chunks. A chunk is a 1KB block of swap. Hence, you may also need to raise 'swchunk' to be able to define a very large swap space. See:

http://docs.hp.com/en/TKP-90202/index.html

Regards!

...JRF...

Re: swap_memory

Steven E. Protter — Tue, 07 Feb 2006 14:40:36 GMT

Shalom Indrajit,

Note that the normal rules for swap setup do not apply to a system with so much memory. You may do fine with swap set to half of physical memory or equal to physical memory.

Setting it to 88 GB on a system that never pages or even reserves a fraction of that is a waste of disk space.

SEP

Re: swap_memory

DCE — Tue, 07 Feb 2006 14:46:00 GMT

Make sure you have the kernel parameter

swapmem_on=1

This allows you to use psuedoswap.

Re: swap_memory

Indrajit_1 — Tue, 07 Feb 2006 15:06:29 GMT

Hi All;

Yes, the output of the command sysdef shows that the max size can be 16384. But is there any dependency for increasing the maxswapchunks ?

Cheers
Indrajit

Re: swap_memory

Don Morris_1 — Tue, 07 Feb 2006 15:09:57 GMT

The only dependency for increasing maxswapchunks is that you have sufficient memory for the kernel to allocate the resulting structures (these aren't that big, so in general if you need to increase it -- do so, you aren't going to miss a few kb of memory).

As others have mentioned, in your case you'll have to increase swchunk as well (since the default swchunk value plus the maximum of maxswapchunks only gets you to 32Gb of swap).

Re: swap_memory

Indrajit_1 — Tue, 07 Feb 2006 17:48:08 GMT

Hi All;

Thanks a lot for ur suggestion.I need to modify the kernel parameter. Hope it will work fine.

Cheers
Indrajit