1. A BDW with a length field of 4 would give you a DASD record with KL=0,
DL=4,
which does not generate a UE.
2. I haven't looked at the code for anything newer than 3420 GCR (6250 BPI),
and have never tried it on 3480 or later, but I would expect wonky results
for short blocks. I don't recall what the SMF
dump utilities do about this.
--
Shmuel (Seymour J.) Metz
http://mason.gmu.edu/~smetz3
________________________________________
From: IBM Mainframe Discussion List <[email protected]> on behalf of
Paul Gilmartin <[email protected]>
Sent: Thursday, February 22, 2018 4:25 PM
To: [email protected]
Subject: Re: Count with no Data and no Key ? (CKD internals again)
On Thu, 22 Feb 2018 15:55:49 +0000, Seymour J Metz wrote:
>I seriously doubt that; it would generate a Unit Exception trying to read the
>second record of the member. You're clearly misinterpreting something.
>
>There is a EOF after the directory and an EOF after each member. There is no
>EOF in the middle of a member.
>
Makes sense.
Now, just curious, what about a block with a data length of 4, where the data
are a BDW with a count of 4?
Also, just curious, I understand that on tape a block <18 (? still?) is bypassed
as a noise record. But it's possible that with RECFM=VB the last block might,
by happenstance, consist of as few as 8 bytes (BDW=8; RDW=4). How do
tape drivers deal with this? Poorly? With RECFM=VBS, a null segment could
be used for padding.
-- gil
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