I would say leave the RAID at 2x7 drive RAID 5. I had to make the same decision about a week ago and that's how I left my storage. No one I spoke with really suggested 50 as a good idea. Yes, you will probably get a performance gain due to the fact that you have a set of 14 drives, instead of 7. Its really your choice. Its a matter of better performance with the set of 14 drives compared to the safety of being able to keep your data online if a controller goes offline and keeping one extra layer of complexity off your data set by not software striping across controllers.
Do you need more space than one 7 drive bank can give you? I simply broke off some data into the second controller, so instead of having one bank 90% full, I have one 50% and the other 40%.
Michael Dhaliwal
Apple Certified: ACHDS, ACTC
Apple Product Professional
Loyola Press
3441 N. Ashland Ave.
Chicago, IL 60657
"If IT was easy
Everyone would do IT"
-----Original Message-----
From: macos-x-server-bounces+dhaliwal=email@hidden on behalf of Ken Carlile
Sent: Fri 10/29/2004 6:40 PM
To: Piers Uso Walter
Cc: Mac OSX Server
Subject: RE: Xserve RAID: RAID 5 set using more than seven drives?
I suppose what I'm getting at is, is RAID 50 less safe than a pair of RAID 5s?
I use the software RAID 1 on my OS drives in general, but use plain vanilla RAID 5s for Xserve RAID arrays. I've never tried anything with a 0 in.
-----Original Message-----
From: Piers Uso Walter [mailto:email@hidden]
Sent: Fri 10/29/2004 4:36 PM
To: Ken Carlile
Cc: Bill Lloyd; Mac OSX Server
Subject: Re: Xserve RAID: RAID 5 set using more than seven drives?
Am 30. Okt 2004 um 00:44 schrieb Ken Carlile:
> What happens if one of the drives goes or if the software component
> (0) goes?
If one of the drives goes, its RAID 5 set is degraded (no longer
redundant), but will still continue to work. As soon as the RAID set is
rebuilt using a spare drive (e.g. automatically using a hot spare), the
RAID set is non-degraded and redundant again. In a 50-scenario, you may
even loose two drives simultaneously, as long as both of them are in
different RAID 5 sets.
I guess, a failure of the software RAID (0) would be comparable to the
RAID controller failure as described by Bill Lloyd. Replace "Swap in a
new RAID controller" by "restart the software RAID (restart the server
OS?)" and the rest should be more or less applicable.
With kind regards
Piers
--
Piers Uso Walter <email@hidden>
ilink Kommunikationssysteme GmbH
> -----Original Message-----
> From: Bill Lloyd [mailto:email@hidden]
> Sent: Fri 10/29/2004 3:33 PM
> To: Ken Carlile
> Cc: Mac OSX Server
> Subject: Re: Xserve RAID: RAID 5 set using more than seven drives?
>
> It is safe for data, because if a RAID controller goes bad, you won't
> lose data. Swap in a new RAID controller, it can read the RAID set
> info off the drives, and you're back up and running in no time. If you
> have a spare controller on hand (i.e. you purchased a spares kit), this
> swap takes 30-60 seconds.
>
> However, it does have "uptime" implications. If a controller goes, the
> entire volume (that is, both halves) goes offline for the duration.
> This effectively doubles your chances of losing availability. It's two
> "single points of failure" and some people won't tolerate ANY, so if
> that's your goal, it's not a recommended approach.
>
> Cheers,
>
> -Bill
>
> On Oct 29, 2004, at 2:23 PM, Ken Carlile wrote:
>
>> My question is, is RAID 50 safe (redundant)? My head gets confused
>> when I try to think about raid systems greater than 5.
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