Hi Trevor:
To my knowledge, with the SSA RAID-5 arrays you are able to configure
anywhere from
2+P up to 15+P in the same RAID-5 group. Keep in mind that you are still
only
protected from a single disk failure, since there is a single parity disk.
I believe that increasing the number of data disks in the group will
probably
decrease performance, since every transaction to the RAID group will require
more physical I/Os. You won't get any additional protection, either.
The best thing to do is to configure 1 or more SSA Hot Spare drives on the
adapter. That way you can be assured that if a disk fails in the RAID
group,
you will have the Hot Spare take over immediately, reducing the window that
you are exposed to a second failure. Then remember to replace the failed
disk
ASAP!
Let me know if you have any more questions.
Thanks!
--------------------------------------------------------------
Matt Cleland mcleland AT msiinet DOT com
Matt Cleland mcleland AT msiinet DOT com
Midland Systems, Inc. (618) 345-0864
St. Louis, MO (618) 346-1779 FAX
> -----Original Message-----
> From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU]On Behalf Of
> Trevor Foley
> Sent: Sunday, July 05, 1998 11:32 PM
> To: ADSM-L AT VM.MARIST DOT EDU
> Subject: SSA Raid arrays
>
>
> Hi,
>
> We use SSA disks for all of our storage pools in a Raid-5, 6+P (6 drives
> plus parity drive) configuration. We are about to reconfigure our
> storage pools and we are reviewing our options.
>
> I'd like to get some idea from other as to whether 6+P is appropriate.
> Would less data drives per parity drive offer significantly greater
> protection? Or are we able to increase the number of data drives without
> significantly reducing our protection?
>
>
> Trevor
> ------------------------------------------------------------------------
> ------------------------------------------------
> Trevor Foley
> Bankers Trust Australia Limited
> Phone: 61-2-9259 3944 Fax: 61-2-9259 2659
>
|