Max SWAP size is still 34Gb?

[Pedro Cirne]

Hi,

I have a HP-UX box with 48Gb RAM, pseudo-swap is on, the swap size is 34Gb, but I'm having problems with SWAP reservation....

Any ideia on how to solve this SWAP size issue?

Thks :)

[James R. Ferguson]

HI:

If you don't have the kernel's 'swapmem_on=1' (to enable pseudoswap0) then I'd certainly set that. If/when on, 'swapinfo -t' will show a line labeled "memory".

Regards!

...JRF...

[Pedro Cirne]

Hi,

Yes, pseudo-swap in ON (or enabled).

Btw, this box is hp-ux 11.11...

Is 34Gb the maximum limit for SWAP?

Thks,

[Court Campbell]

Look towards the bottom of this page and I believe you will find your answer.

http://docs.hp.com/en/939/KCParms/KCparam.MaxSwapChunks.html

[Pedro Cirne]

I know that document...that's why I'm asking if 34Gb is still the limit for SWAP :)

Any patch or upgrade available to allow SWAP > 34Gb?

Thks,

[James R. Ferguson · Accepted solution]

Hi (again) Pedro:

To exceed your 34GB swap size, you will need to change 'swchunks' from its default value of 2048, since:

2048 * 1024 * 16384 = 34,359,738,368

Making 'swchunks' 4096 would double your swap size limit.

Regards!

...JRF...

[Pedro Cirne]

Hi James,

You're right, my brain blocked on 34Gb I don't know why :-))))

Thks!

[Court Campbell]

I don't believe that changing swchunk will make any difference. I still think you are limited to 34Gb regardless. That is why I pointed out the doc. If you lok at the swchunk doc it states the same thing.

http://docs.hp.com/en/939/KCParms/KCparam.SwChunk.html

[Court Campbell]

looking around and found this:

http://forums1.itrc.hp.com/service/forums/parseCurl.do?CURL=%2Fcm%2FQuestionAnswer%2F1%2C%2C0xf2ce99f08a51d61190040090279cd0f9%2C00.html&admit=-682735245+1176913311610+28353475

I see where James acquired his knowledge. And now I have learned something new. Got to love the forums.

[Babu A]

James is right, by increasing swchunk parameter, the max swap can be increased.

This is what I have done for my env. Default was 2048.

Tunable Value Expression
swchunk 3454 3454

Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 55264 0 55232 0% 0 - 1 /dev/vgroot/pswap
reserve - 343 -343
memory 12257 1894 10363 15%
total 67521 2237 65252 3% - 0 -

The total bytes of swap space manageable by the system is swchunk * 1 KB * 16384 (the system maximum number of swap chunks in the swap table)

Allowed values
Minimum: 2048 blocks

Maximum: 65536 blocks

Thanks
Babu