topic Re: Shared Memory in Operating System - HP-UX

Shared Memory

AyoungK — Tue, 22 Oct 2002 19:34:46 GMT

On one of our, the Shared Memory support suddenly got disabled (nobody knows how/why).

When I do a ipcs -m, I get the following response,
$ ipcs -m
IPC status from /dev/kmem as of Tue Oct 22 11:13:48 2002
Shared Memory facility not in system.

I increased shmmax to (4L*1024*1024*1024), but still doesn't work.

Please help.

Thanks,
Kimberly Kim

Re: Shared Memory

A. Clay Stephenson — Tue, 22 Oct 2002 19:41:12 GMT

Check to see if the kernel parameter shmem is set to 0. If so, no shared memory code will be included in the kernel.

Re: Shared Memory

keith persons — Tue, 22 Oct 2002 19:41:49 GMT

Kimberly,

May want to check and make sure shmem is enabled in the kernel. It should be by default but it may have been disabled. You can use one of several methods to verify, whichever you prefer, sam, kmtune if available, pr sysdef, you'll want to make sure shmem is set to 1.

Keith

Re: Shared Memory

AyoungK — Tue, 22 Oct 2002 19:45:10 GMT

It's set to 1.

Kimberly

Re: Shared Memory

A. Clay Stephenson — Tue, 22 Oct 2002 19:50:52 GMT

Here is another guess: /stand/vmunix does not match /dev/kmem. That happens when a new kernel has been moved into place but the system has not be rebooted. That condition can cause all sorts of very wierd problems. I also assume that all the other shxxx values are at least reasonable. I suggest that you compare shxxx with their counterparts on another box. I also assume that with your large shmax setting that this is a 64-bit OS.

Re: Shared Memory

AyoungK — Tue, 22 Oct 2002 20:27:59 GMT

The system rebooted after the change but still
doesn't work. I even compared kernel paramaters with same type of system but not much diferrence on the settings.

Kimberly

Re: Shared Memory

A. Clay Stephenson — Tue, 22 Oct 2002 20:40:07 GMT

Kimberly,

Humor me for the moment and clobber the formula. I have a funny feeling that we are dealing with an integer overflow in the evaluation.

Please set it to 1GB (1073741824); that is a known safe value for both 32-bit and 64-bit OS's. You may be behind on SAM patches and that is why this box is having trouble.

If this is 11.11, there is a patch PHKL_24032 that allows shmmax settings of over 1GB in SAM.

Re: Shared Memory

AyoungK — Tue, 22 Oct 2002 20:44:59 GMT

It's 11.20 & ia64.

Kimberly

Re: Shared Memory

Jeff Schussele — Tue, 22 Oct 2002 21:00:23 GMT

Hi Kimberly,

I know this may sound silly, but I've seen it before.....
Is it possible that you have NO shared memory segments in use at this time?
If not, this is the message you'll see.
Is the server up & doing it's normal, full load of work?

You might try firing up a couple of glance sessions both CLUI & GUI & a couple of other resource intensive routines & then check again.

Rgds,
Jeff

Re: Shared Memory

Keith Clark — Wed, 23 Oct 2002 11:41:34 GMT

Hi Kimberly,

Can you post the output of kmadmin -s?

Thanks,

Keith

Re: Shared Memory

AyoungK — Wed, 23 Oct 2002 16:03:24 GMT

The output of kmadmin -s

No module is registered.

For Jeff - the system rebooted yesterday and
currently no user on the machine.
System is up and running normal
but no activity at all.

Kimberly

Re: Shared Memory

AyoungK — Fri, 25 Oct 2002 16:05:12 GMT

It's working now. Like Jeff said, there's no shared memory segments in use at that time.
After few users logged in on the machine, it
started to use.

Thanks everyone,
Kimberly