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HP-UX 11iv2 - What Swap size compare to memory size

 
Alain BLANC
Occasional Advisor

HP-UX 11iv2 - What Swap size compare to memory size

Hello everybody,
I work on 4 rx3600/HP-UX 11.23 with 16Go RAM
The 4 servers swap have 8Go size.
Do I need upgrade swap size regarding Memory size? Is it a standard rule to sizing swap when upgrade memory for example?

Thanks very much for all.
Alain
4 REPLIES
Sajjad Sahir
Honored Contributor

Re: HP-UX 11iv2 - What Swap size compare to memory size

Dear Alian

please see the link
http://docs.hp.com/en/1219/tuningwp.html

thanks and regards

Sajjad sahir
James R. Ferguson
Acclaimed Contributor

Re: HP-UX 11iv2 - What Swap size compare to memory size

Hi:

Your milage may vary. I assume that you have pseudoswap enabled ('swapmem_on'). If you do, you will see a line titled "memory' in the output of 'swapinfo -tam'.

If pseudoswap is enabled you can run with less swap space than physical memory. Whether or not this supports your particular workload can only be known to you.

If you are seeing fork() failures or stack growth failures for insufficient swap, then you will need to increase your swap size. It is not unreasonable to allocate additional device swap to equal your physical memory in this case.

By the way, in 11.31, 'swampmem_on' is set by default and the kernel tunable is obsolete.

Regards!

...JRF...
Alain BLANC
Occasional Advisor

Re: HP-UX 11iv2 - What Swap size compare to memory size

1 question and 2 answers
Sajjad Sahir and James R. Ferguson gave me 2 differents answer and cannot help me more.
These 2 persons help me enormously.

thanks to theses 2 mens and thanks to HP Forum


Steven E. Protter
Exalted Contributor

Re: HP-UX 11iv2 - What Swap size compare to memory size

Shalom,

The old rule was twice ram for swap. As you get to larger ram sizes, you can get away with less. Your current configuration is the minimum requirement to keep the OS stable.

I would be more comfortable with 16 GB of swap on these systems.

SEP
Steven E Protter
Owner of ISN Corporation
http://isnamerica.com
http://hpuxconsulting.com
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Founder http://newdatacloud.com