On Wed Feb 02, 2011 at 09:21:20PM +0700, hansbkk@xxxxxxxxx wrote:
> On Wed, Feb 2, 2011 at 6:36 AM, Roman Mamedov <rm@xxxxxxxxxx> wrote:
> >
> >> I have a RAID5 setup with 15 drives.
> >
> > Looks like you got the problem you were so desperately asking for, with this
> > crazy setup. :(
>
> Please give some more details as to what's so crazy about this.
>
Just the number of drives in a single RAID5 array I think. I'd be
looking at RAID6 well before I got to 10 drives.
> I would think RAID6 would have made more sense, possibly with an
> additional spare if these are large drives (over a few hundred GB?)
>
With 15, RAID6 + spare would probably be what I'd go with (depending on
drive size of course, and whether you have cold spares handy). For very
large drives, multiple arrays would be safer.
> Or is there an upper limit as to the number of drives that's advisable
> for any array?
>
I'm sure there's advice out there on this one - probably a recommended
minimum percentage of capacity used for redundancy. I've not looked
though - I tend to go with gut feeling & err on the side of caution.
> If so, then what do people reckon a reasonable limit should be for a
> RAID6 made up of 2TB drives?
>
As the drive capacities go up, you need to be thinking more carefully
about redundancy - with a 2TB drive, your rebuild time is probably over
a day. Rebuild also tends to put more load on drives than normal, so is
more likely to cause a secondary (or even tertiary) failure. I'd be
looking at RAID6 regardless, and throwing in a hot spare if there's more
than 5 data drives. If there's more than 10 then I'd be going with
multiple arrays.
Cheers,
Robin
--
___
( ' } | Robin Hill <robin@xxxxxxxxxxxxxxx> |
/ / ) | Little Jim says .... |
// !! | "He fallen in de water !!" |
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