File Server and Raid

[Johan Ramm-Ericson]

On Wed, November 15, 2006 08:41, ruscook wrote:
> Hi Richard,
> I'm not an expert and the installer did the next step for me so we'll
> need to get help on that from this list (hey folks????)
>
> Basically as I understand it you have to have the partition marked as a
> Raid partition (which you do). You also have to put a file system on it
> (I'm using XFS where I can and ext2/3 where I must). You now need to use
> the mdadm command to make raidsets of the corresponding raid partitions.
> "man mdadm" will help, but as I said, maybe someone here can provide the
> correct syntax to make this painless (ie. no errors :-)).
>
> The following is what needs correct/validation from an expert. It is my
> current understanding of the process, but as I said, I've not done it as
> it worked from the installer for me.
>
> a) format each partition (not already formatted with a file system, but
> not swap of course)
> b) do a) for each drive
> c) use sudo mdadm command to create a raidset
> d) add the source partition from sda (as I assume this is the one you've
> been using todate) to each set. This is a "degraded" raid as it only has
> one drive/partition in it.
> e) add the mirror from the corresponding partition on sdb and allow to
> raid set to resync
>
> Then when formatted and set up as a raidset you mount the partitions as
> devices and make sure (for example) /dev/md2 (counting starts from 0)
> is /dev/sda3 and /dev/sdb3 and mounted as /home. Then edit /etc/fstab to
> ensure it is automounted.
> entry for this would be something like:
>
> /dev/md0        /           xfs     defaults        0       1
> /dev/md1        /boot       ext3    defaults        0       2
> /dev/md2        none        swap    sw              0       0
> /dev/md3        /home       xfs     defaults        0       2
>
>
> I note you don't have a separate /boot partition. It is advisable to
> have to one, simply and non-technically it helps minimise the risk of
> grub getting confused and is relatively easy to repair if you get a
> problem without destroying your other settings (which can happen
> if /boot is part of /).

On the whole, I agree with your description Russel. However; Richard, it
might be a good idea for you to read this :
http://www.tldp.org/HOWTO/Software-RAID-HOWTO.html

It's sort of dry and technical (most manuals are) but getting some
understanding of what's involved will probably save you headache later...

/johan