Re: 70GB load source and 5 other drives -- MIDRANGE-L

You WILL want more than one drive for the guest if you do any significant I/O. It's NOT for the benefit of the host as you are correct that workload on the host is spread across all available drives there. The rub is that on the client you now have ALL your I/O through one queue. That queue has limited depth. So while the host partition can handle lots of I/O the guest can only get a limited amount into the queue for the host to do. IBM i has ALWAYS wanted arms, arms are good, and it's true even when they are virtual. The minimum recommended for good performance is 6 arms which is then 6 storage spaces on the host.

- Larry "DrFranken" Bolhuis

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

On 4/25/2014 9:11 AM, Steinmetz, Paul wrote:

Rob,

I only created one storage space.
If one storage space is spread across all host drives, why would need more than 1 storage space.
I'm not seeing where additional storage spaces will gain performance.

My guest LPAR is only used for creating DSLO images and/or testing the install of a DSLO image.

My guest LPAR actually IPLs quicker than the hosted LPAR.
I would think it would be the opposite.

Paul

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of rob@xxxxxxxxx
Sent: Friday, April 25, 2014 8:49 AM
To: Midrange Systems Technical Discussion
Subject: RE: 70GB load source and 5 other drives

Replace "drives" by "storage spaces".
You should not just create one big storage space for the guest.
You should create 6 or more for performance reasons.
Yes, when you do a CRTNWSSTG it will spread that over all the drives in the ASP you create it.
However, the guest still needs 6 'logical units' or LUNs as they talk about it in the SAN world.
You CAN do just 1. I have. Those lpars are also very slow.
Where do you see that your bottleneck is the lack of LUNs in performance tools? I haven't a clue. I'm just standing on the shoulders of giants.

Ok?

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: "Steinmetz, Paul" <PSteinmetz@xxxxxxxxxx>
To: "'Midrange Systems Technical Discussion'"
<midrange-l@xxxxxxxxxxxx>
Date: 04/25/2014 08:39 AM
Subject: RE: 70GB load source and 5 other drives
Sent by: midrange-l-bounces@xxxxxxxxxxxx

Rob and Pete,

I'm confused. When you create a network server storage for a guest LPAR,
you only give it the size, no where do you tell it the number of drives.
If the host lpar has 8 drives, 8 will be used. If the host lpar has24
drives all 24 will be used. The guest storage will be evenly spread across
the number of drives of the host.
Is this correct?

Paul

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx [
mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Pete Massiello - ML
Sent: Friday, April 25, 2014 7:42 AM
To: Midrange Systems Technical Discussion
Subject: RE: 70GB load source and 5 other drives

Rob,

7.2 will need a 70GB load source, and that means when you
create it on the guest side you have to create it larger than 70 to get 70
on the hosted (or client) side. I have been using approximately 79GB when
I create them, and they have worked fine for 7.2. Then if the others are
significantly smaller, I end allocations on that drive to keep the I/Os
more balanced on the spread of the I/Os across the drives

Pete

--
Pete Massiello
iTech Solutions
http://www.itechsol.com
http://www.iInTheCloud.com

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx [
mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of rob@xxxxxxxxx
Sent: Friday, April 25, 2014 7:18 AM
To: midrange-l@xxxxxxxxxxxx
Subject: 70GB load source and 5 other drives

I know that we covered this in a thread but I'm having a devil of a time
finding it. I found it alluded to in
http://archive.midrange.com/midrange-l/201401/msg00542.html

I have a guested system that is currently 279GB. And it's only 30%
utilized. I am doing an unload/reload and I want the 6 "luns".

I figured that I'd make the first one slightly over 70GB (like 75 or 80).
The reason being that it is a very hard halt with the next version of OS,
especially with virtualized disks, and IBM will publish the 'pad' needed
for VIOS, etc.

~300GB - 80GB = 220GB
220GB/(5drives/GB) = 44GB/Drive
So am I better off having 5 'luns' of 44GB each, or,
220GB/(35GB/drive)~=6 drives of 35GB each and having 6 drives of a
somewhat standard size?

Or refigure the whole thing since it's only 30% utilized.
279 * .3 = 81GB

80GB load source and how many of what size additional CRTNWSSTG spaces?
Cause you can see just how much wasted space I'll have with 6 drives of
80GB.

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

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