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Tips for creating DASD and Tapes

 
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Ganesh Kalam
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Joined: 11 Aug 2005
Posts: 45
Location: India

PostPosted: Tue Feb 26, 2008 9:56 pm    Post subject: Tips for creating DASD and Tapes
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I need to know what steps need to be taken while creating DASD or TAPE datasets, to avoid permanent retention of files and also to achieve optimum performance.

For eg.. BLKSIZE=0
EXPDT=98000

If you have any tips like these, please post.
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dick scherrer

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Joined: 23 Nov 2006
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PostPosted: Tue Feb 26, 2008 10:28 pm    Post subject:
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Hello,

You need to talk with the storage administrators for your system.

They can tell you what preferred on your system for all of your storage allocations.
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Anuj Dhawan

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PostPosted: Wed Feb 27, 2008 12:15 am    Post subject:
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Hi,

I think every site has it's own MANAGEMENT class specified in there system arcticture. None of the files, DASD or TAPE, is given, by default, a permanent retention unless specified in respective JCLs. However, Storage guys are the best to answer as suggested.

There are no direct tip as such for this.
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expat

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PostPosted: Wed Feb 27, 2008 12:42 pm    Post subject:
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Yes, it is all site specific, depending on how the storage group have set things up.

One little tip, BLKSIZE=0 in certain circumstances causes far more problems than it solves. Code only RECFM & LRECL to avaoid these problems for DASD datasets.
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Anuj Dhawan

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PostPosted: Thu Feb 28, 2008 5:35 am    Post subject:
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Hi expat,

I thought that BLKSIZE=0 actually saves the DASD sapce. if specified, DSN will have BLKSIZE=0 till the DSN is not written to, once respective processing is done with DSN, i.e. written to, it's BLKSIZE is whatever decided by the System (by SMS, right?). If so then I'm little unclear on Your this comment:
Quote:
in certain circumstances causes far more problems than it solves
Please assist.
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CICS Guy

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PostPosted: Thu Feb 28, 2008 5:47 am    Post subject:
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expat wrote:
One little tip, BLKSIZE=0 in certain circumstances causes far more problems than it solves.
Yea, expat, please expand on this.....
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expat

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PostPosted: Thu Feb 28, 2008 1:03 pm    Post subject:
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BLKSIZE=0 will create a dataset with exactly that, usually when the dataset is created but never opened for output. By only coding the RECFM and LRECL parameters the SDB routines detect no BLKSIZE specified and are invoked to create the dataset with a valid blksize.

HSM does not process datasets with BLKSIZE=0, and given that around 30% of developers are unaware of the RLSE parameter in JCL, they just use up space for no good reason and then come whinging to me when they run out.
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Anuj Dhawan

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PostPosted: Sat Jan 10, 2009 5:17 pm    Post subject:
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Hi,

Coming back to this thread after a while, but you (Expat) are still here, so I can ask some more dumb questions..I know.. icon_smile.gif
expat wrote:
HSM does not process datasets with BLKSIZE=0
is it good or bad ? If HSM is not going to process them - does that mean 'am actually saving some CPU seconds - in this manner is it good or bad ?

Quote:
and given that around 30% of developers are unaware of the RLSE parameter in JCL, they just use up space for no good reason and then come whinging to me when they run out.
So does that mean using RLSE with BLKSIZE=0 is rather appropriate ? If BLKSIZE is already coded to zero, how the "they were run out" of sapce, please assist.

I might run some test for this but there are two reasons why I can't do that - my Mainframe is not "up" and even if I run some tests I don't know where exactly to look at to know if "that combination" had some effect ... icon_neutral.gif
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expat

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PostPosted: Sat Jan 10, 2009 7:12 pm    Post subject:
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Quote:
is it good or bad ? If HSM is not going to process them - does that mean 'am actually saving some CPU seconds - in this manner is it good or bad ?

HSM will attempt to process the datasets and complain that the dataset has an invalid blocksize, and write an error message in the backup / migrate logs.

Quote:
So does that mean using RLSE with BLKSIZE=0 is rather appropriate ? If BLKSIZE is already coded to zero, how the "they were run out" of sapce, please assist.

RLSE and BLKSIZE are independant. My comment was that a lot of developers do not use RLSE in their JCL and allocate space and not use it. I usually set up the MGMTCLAS to release unused space for , so no longer a problem for me.

So, testing combinations of RLSE and BLKSIZE=0 should not yield any useful information.
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