I don't pretend to understand how all this fits together, but there is indeed a
difference between 'LPAR boundary' and Storage Increment Size (SIS). We have a
z12 and a z13 with similar real storage totals.
z12: Total storage 320 GB
SIS 256M
z13: Total storage 344 GB
SIS 512M
SIS seems to represent the z/OS minimum for LPAR definition and CF STOR
commands. We discovered when setting up the z13--using Activation profiles
copied across from a z196--that one LPAR defined as 768 MB was invalid on the
z13 HMC. It had to be increased to 1 GB to be accepted in the Image profile.
However, that same LPAR actually initialized with 1 GB extra of unassigned
storage, a total of 2 GB.
So SIS is the minimum amount that can be manipulated at the z/OS (LPAR?) level,
while the hardware (PR/SM) boundary determines how storage is divvied up
despite Image activation profile values.
.
.
J.O.Skip Robinson
Southern California Edison Company
Electric Dragon Team Paddler
SHARE MVS Program Co-Manager
323-715-0595 Mobile
626-302-7535 Office
[email protected]
-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf
Of Peter Hunkeler
Sent: Wednesday, November 16, 2016 7:53 AM
To: [email protected]
Subject: (External):AW: Re: Real Storage Display
>I discussed this further with Jim Mulder. The z12, where I recently noticed
>the 'unassigned' value, introduced 2 GB pages, one of whose consequences is
>that LPAR boundaries are rounded up as needed to the nearest 2 GB boundary. If
>an image profile specifies any other value, the 'excess' is displayed as
>unassigned storage. It can be configured online to the owning LPAR but cannot
>be allocated to any other LPAR, hence 'unassigned'. As Jim and I talked, I
>recollected a past conversation with a local CE to that effect. The LPAR in my
>display recently got 15 GB of storage added to it. The resulting odd value
>left 1 GB unassigned.
Well this was my first tought when I saw the stroage assigned was an odd number
of GBs: Maybe the hardware assignes storage in 2GB increments. This would
explain the 1GB uassigned to align to the next 2GB boundary.
I usually try to verify before posting, so I looked at the z13 Technical Guide
redbook and found the table below (only parially coied here). I read there that
an LPAR having less than 256GB of mainstorage (yours) will have a granularity
of 512MB. Well, I thougth, wrong trace, and did not post.
After your post, either I misinterpret the table in the redbook (most probably)
or the table is in error (not likely). So the table must indicate the minimum
amount of storage that can be varied online or offline depending on the total
amount of storage assigned. True?
Table 3-7
Logical partition main storage granularity Logical partition:
Largest main storage amount.............Main storage granularity
-----------------------------------..............--------------------------------
Main storage amount
<= 256 GB ..........................................512 MB
256 GB <
main storage amount
<= 512 GB ..........................................1 GB
512 GB <
main storage amount
<= 1 TB ................................................2 GB
--
Peter Hunkeler
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