Re: Disk requirement (performance-wise) on a Power 7 replacing a System i 520

On the subject of p5 to p6/7 migrations,
Is there a guide on how to characterize the performance a CTL/DISKS pair
offers?
I mean, i've got a big machine to spec and it feels like i'm just
ballparking it:
ProdA











6 CTLS 2780 With 12 4327 Disks/each 70,56 c/u Total Cap: 4657

1 CTL ???? With 2 4327 Disks/each 70,56
Total Cap: 71

1 CTL 2780 With 12 4328 Disks/each 141
Total Cap: 1551

3 CTLS 2748 With 15 4318 Disks/each 17,54 c/u Total Cap: 737


Total Arms: 131



Net Total: 7015 Proyected: 8418












ProdB











1 CTL 573D With 4 4327 Disks/each 70,56 c/u Total Cap: 212

2 CTL 571B With 4 4327 Disks/each 70,56 c/u Total Cap: 423

1 CTL 5580 With 6 4327 Disks/each 70,56 c/u Total Cap: 353


Total Arms: 18



Net Total: 988 Proyected: 1185
The ProdB Machine is easy, 1 or 2 controllers with a dozen or two of 141Gb
disks takes care of it (or if going the SAS route 2 controllers with 6
300Gb drives each)
But the ProdA Machine is where i draw a blank. Those 45 4318s hooked to
ancient 2748s must be bringing the performance down hard, but, do i ignore
them arm-wise or do i take them into account?
I think 3 or 4 EXP24 enclosures with dual 2780s or EXP24S with dual 5908
(or 5906/4, depending on the CEC) might work.
But i've only got cache size of each controller to compare, when a 5908
hooked to sas drives should stomp a 2780 or 5580 hooked to scsi drives...
Must be p6 hardware since they're stuck on v5r4...
Haven't got access to anything more than a rackconfig but all the disks are
RAID5'ed.
I like these thought exercises...

Best Regards,



On Wed, Oct 23, 2013 at 11:54 PM, DrFranken <midrange@xxxxxxxxxxxx> wrote:

I AM Larry, and that's what I said, just more succinctly and with fewer
words. :-)


- Larry "DrFranken" Bolhuis

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

On 10/23/2013 9:37 AM, Sue Baker wrote:

I'm not Larry, :) but I'll say R6 offers superior protection
compared with R5+hs. In order to get into the "risk" of data
loss category, you have to lose 2 drives in a RAID6 array. You
are at risk while the rebuild is occurring on the RAID5 array
once a drive fails.

--
This is the Midrange Systems Technical Discussion (MIDRANGE-L) mailing list
To post a message email: MIDRANGE-L@xxxxxxxxxxxx
To subscribe, unsubscribe, or change list options,
visit: http://lists.midrange.com/mailman/listinfo/midrange-l
or email: MIDRANGE-L-request@xxxxxxxxxxxx
Before posting, please take a moment to review the archives
at http://archive.midrange.com/midrange-l.