Re: Disaster recovery planning

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• In reply to: Sue Blake: "Disaster recovery planning"
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Date: Tue, 24 Jun 2003 13:37:52 +0100
To: Sue Blake <sue@welearn.com.au>

On Tue, Jun 24, 2003 at 09:12:14PM +1000, Sue Blake wrote:
> Here's how I plan to recover a system from a level 0 backup to
> new hardware, if ever the need arises:
>
> 1. boot off installation CD (or floppy??)
> 2. disklabel, make filesystems (using sysinstall)
> 3. restore root filesystem and mount it
> 4. change fstab and various configs to work with new hardware
> 5. boot in single user mode, fix fstab and devices, restore other filesystems
> 6. boot multiuser and fix anything that still doesn't work
>
> I'm upgrading using cvsup and don't have recent CDs.
> I know I can make my own bootable CD to keep for this purpose, but I
> don't want to rely on it being found in a crisis if there is a more
> generic method.
>
> Can I do this by booting off an _old_ FreeBSD CD? How old, I mean,
> what sort of changes do I need to look out for?
>
> I think I need the fixit CD too, I couldn't just use the holographic
> shell even if feeling masochistic... or could I?
>
> Could it be done just using a couple of quickly downloaded boot
> floppy images, in which case I'd only need to document the URL for
> the current floppies?

Refreshing to see someone thinking about these sort of things well
before the disaster actually happens.

I think that so long as you've got access to installation media for
the same major version as the system you're trying to recover and that
you can access a) your backup media and b) your hard drive from
eg. the system booted from the live filesystem CD, then you're
covered. In fact, it's clearly going to be a good idea to restore the
data to your hard drive without having to have the system booted from
that drive. Pulling the disk from the machine to be recovered and
temporarily mounting it in another system is an alternative.

You need the same major OS version because of things like the new UFS2
support in 5.x --- although you could partition a drive, build
filesystems and recover the 5.x data from backup using 4.x install
media, you'ld have to create UFS filesystems.

I can't remember off-hand exactly what commands are available on the
install floppies -- I think you get dump(8) and restore(8), but not
tar(1). Booting from the live filesystem CD gets you all the usual
suspects.

If you are using a backup software package not included in the
standard FreeBSD installation, then you've got to keep an installable
copy of that software with your backup media -- after all, the backups
are pointless if you can't recover the data from them. You could even
go as far as creating your own customized install CD, which builds the
filesystems etc. and runs the recovery program: depends just how much
effort you want to put into something you hope you'll never have to
use for real.

        Cheers,

        Matthew

-- 
Dr Matthew J Seaman MA, D.Phil.                       26 The Paddocks
                                                      Savill Way
PGP: http://www.infracaninophile.co.uk/pgpkey         Marlow
Tel: +44 1628 476614                                  Bucks., SL7 1TH UK

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