0000001409bd2345-dmarc-requ...@listserv.ua.edu (willie bunter) wrote:
Good Day To All,
What is the maximum number of cyclinders that can be used to define a dsn that
is not VSAM EXTENDED. I think it is 4400 cylinders. I was trying to allocate
a dsn at 4500 4500 but I kept on abending with IGD17273I ALLOCATION HAS FAILED
FOR ALL VOLUMES........
Finally I was able to allocate the dsn at CYL(4350 4350).
z/OS DFSMS Using Data Sets documents maximum data set sizes, including
limits for both extended format and nonextended format VSAM data sets,
in Topic 1.3.2.3. It says that nonextended VSAM data sets have a limit
of 4GB*.
(4GB* / 56664 / 15) = 5,053 cylinders (approximately)
The actual number of cylinders is certainly somewhat different and
depends, among other things, on the CI size, as the number of bytes VSAM
uses on each track is less than the track length and the number of
blocks per track might still be both model-dependent and is surely
affected by key length. Calculating the exact number at a given CI size
in advance is "left as an exercise to the Alert Reader."
However, if you allocate a data set at a given CISZ you should be able
to look at the High Allocated RBA (HARBA) in the catalog entry from an
IDCAMS LISTCAT command to figure out the ratio between GB and cylinders,
and as that would (a) be much faster, at least for me, and (b) be far
less prone to error, it's probably how I'd figure it out if I needed
every last cylinder's worth of space.
Here's a link to the topic in the z/OS V1.13 level of the book (watch
the wrap):
http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/dgt2d4a0/1.3.2.3?SHELF=all13be9&DT=20110606092005&CASE=
* I believe that is most likely GiB for the pedantic among us.
--
John Eells
z/OS Technical Marketing
IBM Poughkeepsie
ee...@us.ibm.com
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