topic Kernel Changes in Operating System - HP-UX

Kernel Changes

Vito Sarducci — Thu, 31 Jan 2002 14:01:51 GMT

Here is our problem. We have Java runtime processes (JRE's) on our K580 that eats up CPU and memory. The vendor has directed us to use the HP default Java runtime kernel configuration for our HP-UX server.

We changed the kernel parameters back to the default base kernel parameters and modified these additional ones based off the vendors recommendations;

1. MAXUSERS=400
2. NKTHREAD=6000
3. MAX_THREAD_PROC=3000
4. SEMMNI=1024
5. SEMMNS=16384
6. SEMMNU=2048

Now, this is after we went back to the base HP kernel parameters.

When we rebooted, the server would not come back up? What could have caused this and where can I go look for any clues to the server not coming back up?

Your Expertise is appreciated?

Vito

Re: Kernel Changes

Corthouts Carlo — Thu, 31 Jan 2002 14:05:29 GMT

Are you able to boot into single user mode?

Tried booting from the vmunix.prev?

Re: Kernel Changes

Sanjay_6 — Thu, 31 Jan 2002 14:14:51 GMT

Hi,

Boot using the old kernel. At the boot prompt type "bo pri" to boot using the disk on primary path and say "y" to interact with ipl. At the ipl prompt type "hpux -is (;)/stand/vmunix.prev"

This will boot using the old kernel in single user mode. You can then look for the problem. Make a copy of /stand/vmunix.prev in /stand, so that you'll have a copy of good kernel, incase you rebuild the kernel and the current copy gets overwritten.

Hope this helps.

Regds

Re: Kernel Changes

Vito Sarducci — Thu, 31 Jan 2002 14:17:21 GMT

No, we just rebooted from vmnunix.prev at the ISL. We did not try to go into Single User Mode.

What could have caused this? Where can I look?

Re: Kernel Changes

Krishna Prasad — Thu, 31 Jan 2002 14:35:19 GMT

I would first boot of the old kernel to get back. Then I would compare the old system file ( The one used for the vmunix.prev ) to the system file that was used the created the bad vmunix file. I would check and make sure all the drivers needed where in the new system file.

Also, are you running 32bit or 64bit OS on your K580?

Re: Kernel Changes

Vito Sarducci — Thu, 31 Jan 2002 14:45:12 GMT

No, were running 32bit kernel on this server. Were running 11.x in 32bit mode.

Re: Kernel Changes

Roger Baptiste — Thu, 31 Jan 2002 15:07:43 GMT

<>

Where exactly did it stop or hang?? Does it give any error messages at boot time?

<>

You can boot from the old kernel. Use SAM and change the kernel params again and regen the kernel. SAM has a more foolproof way of catching errors and incompatible parameter values during kernel regen.

HTH
raj

Re: Kernel Changes

Vito Sarducci — Thu, 31 Jan 2002 15:40:05 GMT

it would not boot the kernel

Re: Kernel Changes

Vito Sarducci — Thu, 31 Jan 2002 15:42:09 GMT

Where else can I look on the system to find out what might have happened? What logs would indicate there might be a kernel problem?

also, the only thing i see in any logs so far is a magic problem during the reboot.

Magic number wrong (namelist mismatch?)

Any guidance is greatly appreciated?

Vito

Re: Kernel Changes

Tim D Fulford — Thu, 31 Jan 2002 16:23:25 GMT

Hi

I took a look at you kernel params, they look fine (imho) except max_thread_proc=3000, the default is 64!

I do vaguley remember from way back that max_thread_proc should not be set too high else programmers can bring the M/c to a halt by issuing too many threads.

just my 0.02??? worth

Tim

Re: Kernel Changes

S.K. Chan — Thu, 31 Jan 2002 16:31:54 GMT

If you're getting the error
Magic number wrong (namelist mismatch)
it means the content of /stand/vmunix does not match that of /dev/kmem (the kernel that is loaded into memory).