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

Noob Centos Admin centos.admin at gmail.com
Fri Feb 20 06:33:10 UTC 2009


On Thu, Feb 19, 2009 at 4:22 AM, Ray Van Dolson <rayvd at bludgeon.org> wrote:

> The other side of the coin (as I think you mentioned) is that many are
> not comfortable having LVM handle the mirroring.  Are its mirroring
> abilities as mature or fast as md?  It's certainly not documented as
> well at the very least. :)
>

I remember googling for this before setting up a server some weeks ago and
somebody did a benchmark. The general conclusion was stick to md for RAID 1,
it has better performance. IIRC, one of the reason was while md1 will read
from both disk, LVM mirror apparently only reads from the "master" unless it
fails.

Furthermore, given the nightmare of a time I'm having trying to restore a
LVM PV sitting across 3 pairs of md RAID 1, I'll strongly recommend against
tempting fate by using LVM for mirroring as well.

Thankfully for the underlying md mirror, I can at least activate the LVM vg
and offload data in rescue mode even if it won't work off a normal boot.
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