Sue,
Questions all answered.
I wanted to ensure the facts and what was needed if someone from our team inquired about a SSS/HDD mixture.
We do have large IO during large batch jobs, current config of 5913 with 100% SSD is yielding disk response times of .2 ms, occasional spike.
Nightly save, LTO5, creates the largest IO, response varies between 1 and 3.5.
No waits.
R&D LPAR, which is 100% 10k HDD, with 5913, is normally around 2 ms.
Daily save, restores, any long batch jobs, disk response times between 5 to 10 ms, along with some additional wait spikes of 5 to 10 ms.
This is where you see the large difference between SSD and 10k HDD.
Thanks
Paul
-----Original Message-----
From: MIDRANGE-L [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Sue Baker
Sent: Tuesday, December 30, 2014 10:07 AM
To: midrange-l@xxxxxxxxxxxx
Subject: RE: Is STRASPBAL the command to manage/move hot/cold data, P7 V7R1, with internal disks similar to Easy Tier
"Steinmetz, Paul" <PSteinmetz@xxxxxxxxxx> wrote on Mon, 29 Dec
2014 20:22:04 GMT:
Is there a way of seeing the results of a TRCASPBAL % of hot / cold
data, without actually running a STRASPBAL? I would like to run a
TRCASPBAL just to find out %, if possible. Most of our PF/LF are 3rd
party, I would need to get ok from 3rd party to make the unit change,
if I went that HDD direction.
Unfortunately, there is no way to peek into the results of TRCASPBAL. There might be a way to get to similar information using Disk Watcher...at least in theory. Unfortunately, I haven't had time to look into this in much detail.
At this point, I don't think my DASD subsystem is large enough to
justify 2 EXP24S, one for SSD and one for HDD. Can a single pair of
5913 handle both a SSD EXP24S and a HDD EXP24S drawer, or not
recommended. Would 2 pair of 5913 be needed, if I went that direction?
I think I need to do a webcast, YouTube, or something similar to fully answer this part of your question. But let's start with the basics.
The 5887 EXP24S can only contain either SSD or HDD. The feature 5913, EJ0L, and P8 CEC DASD IOAs support mixing SSD and HDD behind them. There are certain restrictions as to which port(s) can be utilized for SSD and maximum quantity of devices.
The hard part with respect to saying whether you should or should not mix SSDs & HDDs behind the IOAs is dependent on workload. I know of many installations where a single pair of adapters drives both SSD and HDD with satisfactory results.
I have also run into a handful of cases where the results were not satisfactory. Each of these were due to different factors.
To attempt to give you guidance without an understanding of your I/O workload would be irresponsible.
--
Sue
IBM Americas Advanced Technical Sales Support (ATS) Power Systems Rochester, MN
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