Thank you, Attila.
Yes, it is Planning for Installation.
It says z/OS can use up to 190 processor in single LPAR (machine limit).
However PR/SM Planning Guide says the limit is 100 processors per LPAR.
There are contradictory informations in the manual - one is 100
processors per LPAR, but other chapter says the limit is 256 processors.
Similar discrepancies can be found in older versions of the PR/SM
Planning Guide.
Remark:
Sometimes theoretical limit is reduced to current physical limit. For
example, older machines had LPAR memory limited to 1 TB while z/OS was
limited to 4 TB at the time. Now manuals say about 4 TB for z/OS, but
sometimes also about same limit for LPAR. Is it true? I saw information
SSC mode LPAR can have up to 16 TB. Is it true for any LPAR mode?
Unfortunately I cannot find an answer.
Note, the discrepancies above have nothing to do with physical machine
limits.
--
Radoslaw Skorupka
(looking for new job)
Lodz, Poland
W dniu 16.04.2021 o 06:49, Attila Fogarasi pisze:
Take a look at
https://www.ibm.com/docs/en/zos/2.4.0?topic=requirements-processor-storage-amount
On Thu, Apr 15, 2021 at 8:37 PM Radoslaw Skorupka <[email protected]>
wrote:
I'm trying to arrange my knowledge about CPU and RAM limits.
Example: current z/OS has limit up to 4 TB of memory. Older versions
(down to 1.8) also had that limit, but older machines had limit for LPAR
memory - up to 1 TB. This time it is not so easy to say what generation,
because LPAR limitation depend on I/O cage. In short, old cards like
FICON Express8 (non-S) means old I/O Cage, means up to 1 TB per LPAR.
Obviously z9 had lower limit because it had less memory (512 GB max).
What is current limit of LPAR memory? It is at least 16 TB (SSC support
it).
Things get more unclear with CPU (CP, zIIP, zAAP) limits. Nowadays it is
possible to run z/OS with 190 CPs defined to LPAR. In the past there
were limitations. And since SMT there is another limitation for SMT mode.
Now questions:
What is current memory limit of LPAR? Is it just all available memory?
What about z/OS pre-1.8? Was the limit of 128 GB the same for all
versions 1.1-1.7?
What are CPU limits for older z/OS?
Is there any table, documentation, or presentation?
What is CFCC memory limit? (CPU is limited to 16 engines).
What about other systems (z/VSE, z/VM, z/TPF, Linux) - are the limits
documented anywhere?
--
Radoslaw Skorupka
(looking for new job)
Lodz, Poland
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