W dniu 2012-02-13 15:21, Thomas Berg pisze:
(This is an answer also to Vernooij.)
Please consider what You do manually when the space is to small (e g B37 etc.),
or You just is unsure: You try a bigger allocation, maybe also extend (or
reduce) the secondary amount. And repeat. Often many times.
Would it be a problem if this (more or less) is automated ? Hm ?
Technically I suppose it's solved by an initial "virtual" allocation filling a
buffer in memory.
Then a disk allocation is done at a threshold with e g 5 cyl.
If that is not enough, add 4 times the amount, 20 cyl.
Repeat this until finish.
Release unused space (from the last add).
This is just an example, it can be done much more sophisticated by the OS.
And the limit of allocation should be set by userid or datasetname properly.
Or maybe by a (e g) LIMIT= keyword.
(I'm using the JCL case as an illustrative example, it should of course be
general system interface.)
Actually space abends in my environment are very very rare. Time and
experience were needed to go there, but the experience + SMS facilities
+ DFSMShsm causes x37 abends almost non-existent.
As I said, z/OS storage requires different approach. On Windows system
programmer opens the file and writes to it. On z/OS he has to answer the
question: HOW MUCH DATA DO YOU EXPECT TO BE WRITTEN. The answer can be
veeeery imprecise, but it is required.
Could it be better? I think so. What about unlimited number of extents?
Or at least, let's say, 3000 per volume? What about multi-volume
PDS(E)s? What about FBA disks?
WAKE UP!
;-)
--
Radoslaw Skorupka
Lodz, Poland
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