topic Re: swap problem in Operating System - HP-UX

swap problem

Patrick Chim — Tue, 27 Mar 2001 03:22:03 GMT

Hi all,

My HP system is low in memory usage. I am wondering why there is no use of the swap device even though it is memory low in this case and it show the following error with the dmesg command

Deferred swap reservation failure pid: 9437
Deferred swap reservation failure pid: 9437

TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 1048576 0 1048576 0% 0 - 1 /dev/vg00/lvol2
reserve - 1048576 -1048576
memory 1566544 1497364 69180 96%
total 2615120 2545940 69180 97%

Regards,
Patrick

Re: swap problem

Steven Sim Kok Leong — Tue, 27 Mar 2001 03:44:28 GMT

Hi,

Your reserve has almost completely used up your device swap. The error message appears because you can no longer reserve more paging space from your device swap.

Extracted from the man page of swapinfo for your convenience:

The reserve (as reflected in swapinfo) is the amount of paging space that could be needed by processes that are currently running, but that has not yet been allocated from one of the above paging areas. When a process is created, or requests additional space, space is reserved for it by increasing the space shown on the reserve line. When paging activity actually occurs, space is used in one of the paging areas (the one with the lowest priority number that has free space available, already allocated), and that space will be shown as used in that area.

As such, you will need to either identify the processes that are requesting for huge paging areas or you can simply add more device swaps.

Hope this helps. Regards.

Steven Sim Kok Leong
Brainbench MVP for Unix Admin
http://www.brainbench.com

Re: swap problem

Patrick Chim — Tue, 27 Mar 2001 04:16:54 GMT

Steven,

But why it show 0 in the percentage use of the dev swap ?

Regards,
Patrick

Re: swap problem

Steven Sim Kok Leong — Tue, 27 Mar 2001 05:06:36 GMT

Hi,

The paging space is reserved before being actually used. When the space is fully reserved, no other process(es) can reserve that space. The device swap is not yet being used, just reserved, thus the device swap is 0% utilised.

Hope this helps. Regards.

Steven Sim Kok Leong
Brainbench MVP for Unix Admin
http://www.brainbench.com

Re: swap problem

Patrick Chim — Tue, 27 Mar 2001 08:40:37 GMT

Hi,

Can you tell me how to modify the swap device so that it can be used ?

Thanks,
Patrick

Re: swap problem

Steven Sim Kok Leong — Tue, 27 Mar 2001 09:05:16 GMT

Hi,

You have to identify the programs/processes that are reserving so much paging area. This will aid in resolving your problem.

To workaround this problem, I believe you just have to configure more device swap. That reserving error message will not appear if you have sufficient device swap.

Hope this helps. Regards.

Steven Sim Kok Leong
Brainbench MVP for Unix Admin
http://www.brainbench.com

Re: swap problem

Dale Corrington — Tue, 27 Mar 2001 16:55:54 GMT

I have the same problem. Mine started when I upgraded from 10.2 to 11. HP has some patches to fix memory leaks. If you don't have any applications running but all of swap is in reserve you may have same problem. The quick and temporary fix is to reboot. For more info
see my post on 3-26-01 "out of memory"

Re: swap problem

Henry Weldon — Wed, 28 Mar 2001 16:58:43 GMT

You do not want to have any swapping going on if possible. But you must make sure you have enough free swap space for additional programs to start up, ie Reserverd swap area. One thing you need to watch out for is that HP changed the default kernel parm, "dbc_max_pct" from 10 to 50% when they went to HP-UX 11.x Check this and change it back to 10%.

Re: swap problem

SSP_1 — Fri, 28 Dec 2001 09:47:45 GMT

Hi Friends,

Right now we r in the process of rebooting the system. But at the same time could anyone of you pl let me know what are the patches we have for hpux11.00[hp9000/A500] os to fix the memory leak problem?