[CentOS] Migrating to RAID

[Alan Hodgson]

On Thursday 10 December 2009, Matt <lm7812 at gmail.com> wrote:
> I have CentOS 4.x installed on a single 500GB SATA drive.  Drive is
> about 10 percent used.  I would like to migrate to software RAID 5
> without reinstalling the OS.  Was thinking 3 500GB drives.  Is that
> possible or must I reinstall?
>

In theory you can create a 3-drive RAID-5 with a "missing drive", rsync your 
filesystems over, and then repartition and force the existing drive to 
rebuild in. 

You can't boot off a RAID-5, so you'll need to put /boot on a separate 
partition, also preferably raid-1'd on at least 2 of the drives.

It's not terribly hard but it's possibly to mess up and nuke your good drive 
before you're ready, so you should have a full backup on yet another drive 
anyway, and if you have that you might as well just build up a new system 
on the 3 drives and then restore your old filesystems over it.

-- 
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damn monkey was just too fast."