Re: Starting Raid on 2nd Raid Card, adding 6 disks

Note: These comments apply to SCSI Drives, SAS RAID performance and configuration is DIFFERENT.

The performance delta between a three drive RAID set and a four drive raid set is HUGE. As Rob mentioned, three drive RAID sets are PA-THE-TIC. The performance delta between four drives striped (meaning 4, 5, 6, or 7 drives in the set) and 8 drives striped is vastly smaller.

I wouldn't be sweating the 6 drives here especially given they are additional drives and not the only drives in the system.

- Larry "DrFranken" Bolhuis

www.frankeni.com
www.iDevCloud.com
www.iInTheCloud.com

On 3/15/2014 9:56 AM, Jack Kingsley wrote:

Rob, thanks, that makes sense, only purchased 6 drives unfortunately.


On Sat, Mar 15, 2014 at 8:08 AM, <rob@xxxxxxxxx> wrote:

If these are SCSI drives you would be better off if you started out with 8
(or more) disks than 6.
3 drives: Raid striping is across only 2 drives. Ultimate performance
killer. Legendary. Across multiple OS's, not just IBM i. Google 3 drive
raid set.
4-7 drives: Raid striping is across 4 drives.
8 or more drives: Raid striping is across 8 drives.

Can you see the difference there?


Rob Berendt
--
IBM Certified System Administrator - IBM i 6.1
Group Dekko
Dept 1600
Mail to: 2505 Dekko Drive
Garrett, IN 46738
Ship to: Dock 108
6928N 400E
Kendallville, IN 46755
http://www.dekko.com





From: Jack Kingsley <iseriesflorida@xxxxxxxxx>
To: Midrange Systems Technical Discussion <MIDRANGE-L@xxxxxxxxxxxx>
Date: 03/14/2014 08:37 PM
Subject: Starting Raid on 2nd Raid Card, adding 6 disks
Sent by: midrange-l-bounces@xxxxxxxxxxxx



Can you start raid, add drives and balance data to ASP1 with the system
up,
or do you need to it in a controlled environment using SST/DST.
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