[ILUG] Why RAID

[Paul Jakma]

On Tue, 13 Jul 2004, John P. Looney wrote:

> No, if you raid 1 before you raid 0, you can lose half you disks,

well, 1 over 0 or 0 over 1 - makes no difference to reliability 
really. But I have had 4 disks, I'd go for RAID-5 on 3 + hot spare.

> and keep going (though they have to be the right half!).

Indeed.

> It's the configuration Sun recommend in all installations to people 
> that have loads of money; RAID1+0 and a hot spare (or two).

Hmm, the E2xx cluster at alphyra was installed by sun with mirrored 
RAID-5 arrays.

> I'd only recommend it in cases where there are a lot of writes - 
> like mail and database servers. It'll beat RAID5 by a good margin.

i'd much prefer raid-5 + spare, or mirrored raid-5 :)

> I'll be building a new mail server soon, with 6 15kRPM SCSI disks 
> in it; I'll have a go with bonnie, and see what we get for RAID1+0 
> and RAID5.

Be interesting. Try the new RAID-6 too, just for kicks.

> John

regards,
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