When a System Dies; Getting back in operation again.

Doug Poland doug at polands.org
Mon May 4 18:32:23 UTC 2009

On Mon, May 04, 2009 at 04:30:53PM +0200, Jonathan McKeown wrote:
> On Monday 04 May 2009 15:59:14 Jerry McAllister wrote:
> > On Mon, May 04, 2009 at 10:31:16AM +0200, Jonathan McKeown wrote:
> >
> > > If you have kept the right information beforehand, you can
> > > actually restore your dumps onto ``bare metal'' without doing a
> > > partial install first, and with the same newfs settings for each
> > > partition as you originally had. You need to use bsdlabel and
> > > dumpfs -m and keep the output for rebuilding. The rest of this
> > > message is the details.
> >
> > If you have a specific reason to want your new filesystems' to have
> > identical superblock info, you can use dumpfs -m, but you don't need
> > to worry about all that. ? Just fdisk, bsdlabel and then let newfs
> > take its defaults.
> Which of your filesystems currently has softupdates disabled? You may
> not care - but the point is that using dumpfs in the way I described
> will preserve that information (along with all the other tuning
> options) for people who do care.
> If you're restoring a complete machine from backup, the less you have
> to think about, the better. Knowing that my filesystems are going to
> be restored with whatever tuning options I was previously running
> with, without my having to try and remember, gives me peace of mind
> ahead of time.
Excellent discussion.  Along the lines of "the less you have to think
about",  is there a technique for restoring geom meta-data on bare
metal?  Say you have a system built upon gmirror and gjournal.  One must
manually create the mirror and journal before restoring from dump.  But
the vital geom meta-data describing your mirror/journal is on the dump.


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