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

Well first let me commend that this is quite the collection!
17G 10K on 100MB Cache cards from 1995(?) all the way up to 141G 15K Drives on 'reasonably' current cards. But you have a LOT of arms there so a fair bit of capability.

Sue already named the big tools and with a system this big I would use them. :-)

- Larry "DrFranken" Bolhuis

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

On 10/24/2013 12:22 PM, Roberto José Etcheverry Romero wrote:

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.

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