No. I think there is no significant performance difference between
half-track and full-track blocksize and there is significant difference
in support of nonstandard blocksize.
I just wanted to advice, nothing more.
For tapes (especially physical ones) I would suggest the largest
blocksize whenever possible. However this is different story.
--
Radoslaw Skorupka
(looking for new job)
Lodz, Poland
W dniu 07.03.2021 o 21:37, Joseph Reichman pisze:
In other words you don’t think bufno / ncp
And overlapped I/O will produce anything significant
On Mar 7, 2021, at 2:14 PM, Radoslaw Skorupka <r.skoru...@hotmail.com> wrote:
Joseph,
There is some nuance missing. I wrote about *significant* difference. Actually
I should say the difference is negligible.
I really don't know your application, however I guess such blocksize change
will not help you. I have suggested some other techniques to consider instead.
IMHO endusers should usually avoid using specific, rare (and bizarre)
techniques. Usually simple is better. Usually my problem was solved several
times. YMMV. As usual.
--
Radoslaw Skorupka
(looking for new job)
Lodz, Poland
W dniu 07.03.2021 o 16:56, Joseph Reichman pisze:
If you read a larger number of bytes into core let’s say above the bar less I/o
should speed things up no ?
On Mar 7, 2021, at 10:40 AM, Radoslaw Skorupka <r.skoru...@hotmail.com> wrote:
W dniu 06.03.2021 o 16:50, Laddie Hanus pisze:
LBI is available on DASD the largest block that will fit on 1 track, on the
3390 thats about 56K. Logical record (LRECL) is still limited to 32760, This is
for new datasets being written. Existing datasets will read one block per i/o
and will be no larger than what written. this is for BSAM read/check. manual
DF/DSS Advanced services under the DEVTYPE macro will has a table of largest
blocksize per decice type
The problem is I have never seen LBI block on DASD.
Can I allocate such dataset using ISPF 3.2 or JCL DD ?
Can I copy existing LBI dataset using IEBGENER or IDCAMS?
It's more or less like long member names in PDSE. They exist, however I haven't
found any.
And I think it is not only my observation.
From the other hand large blocks on tape are widely used and supported by
existing system tools.
Last, but not least: author of the thread wants better performance. I would not
expect significant performance improvement by changing BLKSIZE =half track to
whole track.
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