Re: Disk MTBF

From: Fred A G <nospam_at_allowed.localhost>
Date: Fri, 2 Mar 2001 00:54:18 +0100
Message-ID: <5hBn6.5593$hi2.16367@nntpserver.swip.net>

"Roger Menhennett" <r.menhennett_at_lmco.com> wrote in message news:3A9BE9CD.B783FE73_at_lmco.com...
> Am wondering what the probability of disk failure is in the following
> scenarios for the first year, second year, etc. (assume one machine
with
> a
> disk mtbf of 50000hr.).
>
> 1. One disk.
> 2. Six disks.
> 3. Six disks configured as raid1.

> Am concerned with how much quantifiable confidence one can put in a
> raid device to substitute it for backups. Besides device failure,

None, nada, nil! A raid device is not a substitute for backup (where you make a good copy of important data to tapes and place the tapes in the media safe(s))!

Mirroring/redundacy in raid is for "protection" against disk failure, nothing more. A six disk simple mirroring raid-1 (3 <-> 3) can stand loosing one to three disks. Make sure you spread disks across several HBAs too, just in case...

Regards
/Fad Received on Thu Mar 01 2001 - 17:54:18 CST