[CentOS] 4 X 500 gb drives - best software raid config for a backup server?

Tue Feb 17 22:01:40 UTC 2009
Ray Van Dolson <rayvd at bludgeon.org>

On Tue, Feb 17, 2009 at 01:52:52PM -0800, dnk wrote:
> Hi there,
> 
> I am currently setting up a server that will house my backups (simply  
> using rsync).
> 
> This system has 4 X 500 gb drives and I am looking to raid for max  
> drive space and data safety. Performance is not so much a concern.
> 
> My experience with software raids in nil, so some of these may seem  
> like pretty dumb questions.
> 
> I was thinking a raid 1 is probably sufficient.
> 
> Would it be best to raid 1 two drives each and LVM them together?

This probably gives you both the best reliability and the best
performance (RAID 10).  You can potentially lose two drives (although
they'd need to be on opposite mirrored subsets) and be OK.

If you want to maximize space, RAID5 would work as well.  You'd get
nearly 1500GB out of this setup but could only survive one disk
failure.

Your other option would be RAID6 which would net you the same amount of
space as RAID10 with four drives and also allow for two drive failures
(any of the drives in this case).  If you anticipate adding additional
drives later, this would allow you to add one drive at a time instead
of requiring a pair.

RAID6 has a write performance penalty, but I imagine it would still
run well enough to handle backups.

I think I might lean towards the RAID6 option in this case.... same
space as RAID10, but allows you to lose *any* two drives and still
maintain functionality at the expense of some write performance.

> 
> My next question would be about how to do this as I have never done a  
> linux software raid.
> 
> D
> 

Ray