topic Re: Kernel backup in Operating System - HP-UX

Kernel backup

Feljav — Thu, 01 Feb 2007 19:19:49 GMT

How can I make a kernel backup in HP-UX 11.11?

Can I copy /stand/vmunix to any directory and use that copy to boot the kernel?
When I boot from an alternate kernel, does this copy automatically become in the current kernel or do I have to change it manually? If so, how do I change it?

Re: Kernel backup

Patrick Wallek — Thu, 01 Feb 2007 20:05:17 GMT

The backup kernel MUST reside in /stand. /stand is the ONLY file system that is accessible when the machine starts booting. If you have a backup in any other file system it will be useless as you will not be able to access it.

Re: Kernel backup

A. Clay Stephenson — Thu, 01 Feb 2007 20:23:08 GMT

Note that normally the current kernel is saved as /stand/vmunix.prev before the new kernel is moved to /stand/vmunix so you should have a backup copy. Wise admins always uintentionally oversize /stand so that another known good copy such as /stand/vmunix.safe can be kept.

Re: Kernel backup

Feljav — Thu, 01 Feb 2007 20:44:28 GMT

But, When I boot from an alternate kernel, does this copy automatically become in the current kernel or do I have to change it manually? If so, how do I change it?

Re: Kernel backup

Patrick Wallek — Thu, 01 Feb 2007 21:07:18 GMT

If you boot from /stand/vmunix.prev, it stays as vmunix.prev. It does not move to /stand/vmunix.

You would have to copy it manually. The steps would be pretty much the same as if you were compiling a kernel manually, though in reverse.

Your better option, if you have to use a vmunix.pref is to copy that to vmunix.good, so you always have a known good kernel (as Clay said above) and then try to figure out why /stand/vmunix didn't work. The normal process of building a kernel creates a vmunix.prev, so you don't want to unintentionally overwrite a good kernel with a bad one. You'd really be in trouble then.