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Another HP-UX swap question

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James Brand
Frequent Advisor

Another HP-UX swap question

When total swap is 100% as shown by swapinfo -tam won't new processes fail to start? I have 32 GB main memory, 16 GB swap, and pseudo swap enabled. Free memory is 4 GB and dbc max is set to 5%. Here's the output:

TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 16384 0 16384 0% 0 - 1 /dev/vg00/lvol2
reserve - 16384 -16384
memory 26327 22056 4271 84%
total 42711 38440 4271 90% - 0 -

Even though the server is not swapping I'm sure I've seen processes fail to start when total=100%. Our policy is not to create swap space on SAN so I'm going to install a 72 GB boot disk with 40 GB of swap space.

Thanks in advance,
Jim
3 REPLIES
Patrick Wallek
Honored Contributor
Solution

Re: Another HP-UX swap question

You are correct. When there is no space left for a process to reserve swap (pseudo swap or device swap) then processes will fail to start.
Emil Velez
Honored Contributor

Re: Another HP-UX swap question

yes

You could put dbc_max down to 3

that would still be 1 GB or so of dbc before it shrinks when memory is full.

You could add filesystem swap with a priority of 2 so you have more swapspace on non-san

filesystem swap is better than nothing.
James Brand
Frequent Advisor

Re: Another HP-UX swap question

I am planning to decrease dbc max, 3% sounds about right.

FS swap is an option but maybe I'll get my outage to install the larger boot drive first.

Thanks to both,
Jim