Specifically, see
http://www.bitsavers.org/pdf/ibm/dasd/reference_summary/GX26-4577-0_3390_Reference_Summary_Jun89.pdf,
This reference Summary booklet contains on p10 the non-trivial
calculation formula for how many physical blocks will fit in a 3390
track, and also contains a chart on p18
And also remember that if the data sets are extended format then each physical
block is 32 bytes larger.
Lennie Dymoke-Bradshaw
https://rsclweb.com
‘Dance like no one is watching. Encrypt like everyone is.’
-Original Message-
From: IBM Mainframe Discussion List On Behalf Of
Radoslaw
There used to be a command on the CBT tape to do track capacity calculations.
--
Shmuel (Seymour J.) Metz
http://mason.gmu.edu/~smetz3
From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of
Radoslaw Skorupka [r.skoru...@hotmail.com]
There's a description of track capacity calculations in one of the DFSMS
manuals; there are all sorts of overhead factors that have to be taken into
account.
--
Shmuel (Seymour J.) Metz
http://mason.gmu.edu/~smetz3
From: IBM Mainframe Discussion List
W dniu 25.10.2021 o 16:44, Oscar pisze:
Hi there,
There's something I'm being missing, but acording to my numbers, there
should be 13, not 12:
Bytes per track: 56,664 bytes
Bytes accessible per track: 55,996 bytes
CI size: 4096
Physical record size: 4096 bytes
Physical records per track
Oscar,
Here is a great Redbook for VSAM, enjoy.
http://www.redbooks.ibm.com/abstracts/sg246105.html?Open
Stay Safe
> On Oct 25, 2021, at 10:54, Oscar wrote:
>
> Hi there,
>
> There's something I'm being missing, but acording to my numbers, there should
> be 13, not 12:
>
> Bytes per
Oscar,
What you're missing is what used to be called the IRG (Inter Record Gap) on
physical disk records.
Now, on modern 3390 formatted disks, it is a more complicated calculation
involving "cells," but it's the same idea; and only 12 4096 byte CIs will fit.
Harry
Inter-record gaps between each physical block take space on the track away from
data, not to mention count and key parts of each physical block (CKD means
count-key-data).
There is actually not any physical reason for IRG between physical blocks any
more since we no longer have physical 33x0
CA size and number of CI that fit in a CA
Stay Safe
> On Oct 25, 2021, at 10:54, Oscar wrote:
>
> Hi there,
>
> There's something I'm being missing, but acording to my numbers, there should
> be 13, not 12:
>
> Bytes per track: 56,664 bytes
> Bytes accessible per track: 55,996 bytes
> CI
Hi there,
There's something I'm being missing, but acording to my numbers, there
should be 13, not 12:
Bytes per track: 56,664 bytes
Bytes accessible per track: 55,996 bytes
CI size: 4096
Physical record size: 4096 bytes
Physical records per track (Bytes accessible per track / physical
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