Re: Use RAID1 mirror as backup during dist-upgrade?

[Scott Gifford <sgifford@suspectclass.com>]

Reiner Buehl <reiner@buehl.net> writes:

> I have a Debian Etch system that runs on a RAID 1 software raid
> system. now I would like to upgrade it to Lenny by splitting the
> mirror off and keep one mirror as a backup. 

Hello Reiner,

I do exactly this when I upgrade a system.  I simply disconnect the
drive I'd like to remain as a backup.  When I am satisfied that
everything is working, I shut the system down, reconnect the drive in
a way that ensures the system will boot from the upgraded drive, then
reboot and use mdadm to restart the mirror (if they are hot-swap
drives the same applies, but you don't need to shut the machine down
to put the drive back in).  If I need to revert to the backup, do the
same thing but make sure the backup drive is the boot drive.

Many systems let you choose which drive to boot from in the BIOS;
those that don't will generally give priority to the first drive on
the first controller of the system.

If I have spare drives, sometimes I will save the old drive as a
long-term backup and put a new drive in.  Then I can stick that in a
USB enclosure to get data from it.  I have never ended up using the
data, though; the upgrades have either worked completely or not at
all.

Hope this helps!

----Scott.