One boot? kernel tune and patch/boot

[Gary Powell_1]

Trying to minimize down time.
If I build a new kernel with kmtune and make it /stand/vmunix but do not boot on it will swinstall use my new values when it rebuilds the kernel as part of a patch update?

Or does swinstall take values from the running kernel?

Thanks,
Gary Powell

[Steven E. Protter · Accepted solution]

Shalom,

You can set your kernel values with sam and choose not to boot the system.

You can change your values with the kmtune command and then do all the preparation steps but not boot.

Your patch install will handle that.

See this procedure:

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=234110

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=105739

Summary: If the system file has been moved and the vmunix file is in place but the system not booted, an swinstall, even one installing patches that updates/patches the
kernel or values will correctly install and make necessary changes.

This DOES increase slightly the risk of ending up with an unbootable server. But it does minimize downtime when it works, which is most of the time.
SEP

[Geoff Wild]

Good question - I founfd this in docs:

"Caution: Ensure that the booted kernel is /stand/vmunix before installing any kernel software. The swinstall process assumes that the system has been booted using the kernel at /stand/vmunix. Installing kernel software or performing an operating system update with another kernel might result in loss of data or other errors."

So, you may be able to - as it seems to look at /stand/vmunix.

Make sure you have a good ignite image - just to be safe :)

Rgds...Geoff

[Sameer_Nirmal]

Hi,

I think swinstall doesn't interact with with kernel parameter values directly either from running kernel or /stand/vmunix file. If you are installing a kernel patch which obviously requires rebuild of new kernel, then it simply pass on control to the kernel build up system procedures/commands for new kernel generation.

As I understand,
When you make kernel parameter value change using kmtune or SAM command, they are written to /stand/system file.
Then "mk_kernel" uses this file ( by default ) copies it to "/stand/build/". This directory is a kernel build up working directory.

When you do "kmupdate" the new generated kernel is marked to move to its destination /stand/vmunix upon next startup.

So even after you don't reboot the system with recently generated kernel with new values, those kernel parameters & values would remain in /stand/system thus getting automatically included in the next kernel build.

[Gary Powell_1]

Thanks to all for the info. Sounded good and I tried kmtune to build a new kernel and moved it and system into place.

Installed patches w/kernel rebuild and reboot. Tuned parameters not in place. Used SAM to change them again and 2nd reboot.

Not sure where swinstall gets it's kernel data.

Thanks anyway.
Gary