topic Re: Secondary swap not active in Operating System - HP-UX

Secondary swap not active

Venky_1 — Fri, 10 Dec 2004 03:09:13 GMT

Hi ,

On HP 11i server, 24GB of secondary swap is defined but there is no activity on these lvols. I tried to start auxiliary swap explicitly as well but no luck.

Server has latest patch bundles of Dec'2003
Any suggestions.

Thanks
Venky

Re: Secondary swap not active

Ivajlo Yanakiev — Fri, 10 Dec 2004 03:30:24 GMT

did you swapon your secondary swap ?

Re: Secondary swap not active

Stf — Fri, 10 Dec 2004 03:40:37 GMT

Hello,

# swapinfo -d

if you don't see your secondary swap swapon it...

Stf ;-)

Re: Secondary swap not active

Venky_1 — Fri, 10 Dec 2004 04:05:55 GMT

secondary swap is available ( 24GB in multiples of 4GB ) but it is not being used.

Thanks
Venky

Re: Secondary swap not active

bhavin asokan — Fri, 10 Dec 2004 04:17:01 GMT

hi,
can you post the

swapinfo -tam output.

regds,

Re: Secondary swap not active

Ivajlo Yanakiev — Fri, 10 Dec 2004 04:29:36 GMT

Sec swap is useing only if primary swap is full :)

Re: Secondary swap not active

Massimo Bianchi — Fri, 10 Dec 2004 04:46:42 GMT

Hi,
what are you kernel parameters ?

please post "kmtune | grep swap"
and
"swapinfo -ma"

HTH,
Massimo

Re: Secondary swap not active

Ralph Grothe — Fri, 10 Dec 2004 04:55:06 GMT

I'd say you're lucky if there's no activity on your secondary device swap.
As someone already said it should only be used after the primary device has been used up.
Or did you intend some sort of interleaving operation by assigning it the same priority?

Re: Secondary swap not active

Nguyen Anh Tien — Fri, 10 Dec 2004 05:31:52 GMT

Swap size ti limited by 3 parameter:
maxswapchunks, swchunk and DEV_BSIZE
The formular is
Swap size: swapchunks x swchunk x DEV_BSIZE
(default DEV_BSIZE:1024bytes).
For Example:
You create 1GB for swap space. and you set:
swapchunks:256
swchunk:2048
then
Swap size=256x2048x1024=512MB
Because of setting, only 512MB swap space can used. If you want to use the other 512MB
swapchunks need to be increased to 521

(you can read "HP_UX Performance and Tuning H4262S A.00" at page 8-17)

Re: Secondary swap not active

Venky_1 — Fri, 10 Dec 2004 07:05:35 GMT

Hi ,

Please find attached txt file for requested details.

Thanks

Re: Secondary swap not active

Ralph Grothe — Fri, 10 Dec 2004 07:26:33 GMT

I'm not sure, but how come that all the other swap devices have got priority 0.
I think you should change the attribute pri= in your fstab to something meaningful.
But I'm afraid to release your swap you need to reboot.

Re: Secondary swap not active

Pete Randall — Fri, 10 Dec 2004 07:26:34 GMT

It's obvious from your swapinfo output that none of your swap space is being used. This is a good thing. It means that you're using memory instead of slow, inefficient swap disk space.

Pete

Re: Secondary swap not active

Massimo Bianchi — Fri, 10 Dec 2004 07:27:17 GMT

Hi,
looks like you are all right.

swap is not used because you do not need it.

Probably you are working in memory, and that's good.

WHat are your applications ?

And WHY do you think that you have to use the swap ? They are avaiable (cfr in swapinfo output), but not in use, since you are not requesting very much RAM.

HTH,
Massimo

Re: Secondary swap not active

Ralph Grothe — Fri, 10 Dec 2004 07:28:47 GMT

Besides, Pete is totally to agree to.
You *don't* want to see any swap usage.

Re: Secondary swap not active

Venky_1 — Fri, 10 Dec 2004 08:53:26 GMT

As swap lvols are not in use, server is getting stuck due to physical memory ( 12 GB ) exhaustion as it is hitting 100%.

Re: Secondary swap not active

SupraTeam — Fri, 10 Dec 2004 10:00:27 GMT

Hello,
did you defin kernel parameter :
swapmem_on

Re: Secondary swap not active

Venky_1 — Fri, 10 Dec 2004 10:14:33 GMT

Yes, it is already defined as mentioned earlier through attached txt file.

Re: Secondary swap not active

Bill Hassell — Fri, 10 Dec 2004 12:56:01 GMT

"As swap lvols are not in use, server is getting stuck due to physical memory ( 12 GB ) exhaustion as it is hitting 100%."

HP-UX is a virtual memory system so using all of physical memory is never a problem. Processes will be deactivated and then rolled out to the swap area as needed. 24Gb is an enormous amount of swap space and will likely never be used. Since nothing is rolling out to the swap area, processes that are failing with memory problems are most likely failing because they are only 32bit programs that need more memory than they can possibly address, or due to shared memory fragmentation in 32bit shared memory. These will help a lot in understanding the limitations of 32bit programs:

ftp://eh:spear9@hprc.external.hp.com/memory.htm

http://docs.hp.com/hpux/onlinedocs/os/memwn1_4.pdf

http://docs.hp.com/cgi-bin/otsearch/getfile?id=/hpux/onlinedocs/os/11i/mem_mgt.html&searchterms=5965-4641&queryid=20030128-153709

http://www1.itrc.hp.com/service/cki/search.do?category=c0&docType=EngineerNotes&searchString=RCMEMKBAN00000027&search.y=12&search.x=20&mode=id&admit=-682735245+1102701301380+28353475&searchCrit=allwords

The last reference (shared memory) may require a software support contract in order to access.

Re: Secondary swap not active

Sridhar Bhaskarla — Fri, 10 Dec 2004 21:56:16 GMT

Venky,

How did you determine that your memory was exhausted?. What tool did you use?. Post your 'vmstat 2 2' output. Look at the 'free' column and multiply it with 4 to get the free mem in KB.

I believe you are getting confused with the 'memory' line in your 'swapinfo' output. It's not to be confused with the memory used. Most likely you haven't changed your dbc_max_pct value. So, there is a good chance 50% of your memory is now used as buffer cache which you don't need.

I suggest you change dbc_max_pct to around 4-6% and min_pct at 2%.

If the above is not the case and if your programs are failing with 'insufficient memory' messages, then anyone of your max*siz(_64bit) parameters are insufficient.

-Sri