[CentOS] RAID5 or RAID50 for database?

Fri May 23 07:59:49 UTC 2008
Rudi Ahlers <Rudi at SoftDux.com>

Warren Young wrote:
> Rudi Ahlers wrote:
>> So, how does it perform with 6 discs for example? Say I have 3 HDD's 
>> in RAID-0, and another 3 in RAID-0, then RAID-1 the 2 RAID-0 stripes. 
> There's actually two kinds of RAID-10.  Some like to say RAID-01 or 
> RAID-1+0 or things like that to distinguish them.  It's a matter of 
> whether it's mirrors over stripes or stripes over mirrors.  You're 
> talking about mirrors over stripes, but I'm talking about doing it the 
> other way around.
> Your way has the advantage of letting you add disks in pairs, but to 
> get that you get only single-disk redundancy: if a second disk goes 
> out, your array is gone, no matter which disk it is.
> If you do it the other way, you have to use groups of 4 (two mirrors 
> striped together) but you get the advantage that with a single disk 
> missing, you can lose another if it's in the other mirror.  Of course, 
> if you lose two in the same mirror, you're toast.
>> And what would you recommend on 8 / 10 HDD's?
> As I said, usually RAID-5 or -6 usually makes more sense with so many 
> spindles.  If you're talking RAID-10 (my way) with so many disks, it 
> starts getting expensive with 8, 12, etc.
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Ok, so it stripping a mirror more redundant then, from what you say? 
But, it's limited to pairs of 4 HDD's, which means a bigger chassis, and 
a mobo / PCI controller that can support 8 HDD's if I want to add more?

But, if I want to use 6+ drives, rather use RAID 6? How does RAID-6 
perform in relation to RAID-5 or RAID-10 (RAID-01)?


Kind Regards
Rudi Ahlers
CEO, SoftDux

Web:   http://www.SoftDux.com
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