The below rather good e-mail from Alan just came in.
And as Alan says, it was not my boot blocks that got corrupted. Instead is was /osf_boot I'm pretty sure.
Greg Freemyer
Internet Engineer
Deployment and Integration Specialist
The Norcross Group
www.NorcrossGroup.com
---------- Forwarded Message ----------
FROM: alan_at_nabeth.cxo.cpqcorp.net
TO: Greg Freemyer <freemyer_at_norcrossgroup.com>
DATE: Fri, 25 Jan 102 15:55:45 -0700
RE: Re: 2 Corrupted Disk Recovery Questions: After the fact
Unless a disk/controller went berserk, it is unlikely that
the boot blocks were scribbled over. I think the code in
the boot blocks tries to hand off the boot to /osf_boot
pretty quickly, which is on the root file system. /osf_boot
takes care of loading the kernel and getting it started.
The disklabel command, with appropriate options, will
write the boot blocks for you. Left to itself with
no options, it writes the blocks for UFS. The "-t advfs"
option tells it to write the AdvFS boot blocks. There's
another option to get no boot blocks, for what that is
worth.
If the root file system is badly enough corrupted to warrant
restoring from backup, then it isn't that much extra to rewrite
the label. The risk, is that if the partition table was
customized that information gets lost. If the label is
still readable you could get the content, note any customizations
and restore those after writing a new label. File system type
information would also get lost and have to restored. A copy
of the disklabel command is on the distribution CDROM, which
can be booted to a single user shell for doing this sort of
work.
Restoring a root backup, nearly as easy, since the versions
of restore and vrestore are there as well. Rather than
blindly mounting the old one and restoreing from backup
it might be cleaner to recreate the file system and then
restore the backup. It also depends on how up to date your
backup is. Not much changes in the root, unless you do it,
but for some customer's that enough to get the backup out
of sync.
One of the system management documents may have a section
on system disk recovery. Check the Master Index. If you
don't have printed copies of the documentation, it is all
on the documentation CDROM in PDF and HTML formats. There
is more AdvFS documentation on the Associated Product CDROM
that has the AdvFS Utilities kit.
Received on Fri Jan 25 2002 - 23:45:06 NZDT