Reminder -- RAID 5 is not your friend

[gmongardi-cGmSLFmkI3Y at public.gmane.org (Grant M)]

Kent Borg wrote:
> One could set up the raid to use a third disk, one that is external SATA 
> or USB. Add it to the mirror and the mirror "rebuilds", giving you a 
> complete copy of the entire system. Now split it off from the mirror and 
> you have a consistent snapshot of the entire box on that one external 
> drive. Do some magic with grub and it might even be sensible as a boot 
> disk for disaster recovery. Take it away as your off-site backup. 
> Further, set up a different external disk to do the same thing and now 
> you can ping-pong between the two off-site backups, always keep at least 
> one backup drive off-site and you will be pretty safe from those pesky 
> "act of God" hazards.

The issue I see with this, is that some of the manufacturers raid
controllers are only manageable during the boot process. So, the plan of
disconnecting it and running the backup would be fine, but
re-integrating it would require rebooting and configuring the controller
to accept what it would now consider a "foreign" drive. "foreign" means
that it has something on it, and the controller (rightly so) won't
automatically add it back into the mirror. IIRC, both Dell and IBM work
this way. HP might let you do this without going through the boot cycle,
but I'm not sure.
Grant M.
-- 
Grant Mongardi
Senior Systems Engineer
NAPC

gmongardi-cGmSLFmkI3Y at public.gmane.org
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