John McKown wrote:
For tape (especially modern tape), I've always here that the optimal BLKSIZE
is as big as you can make it. For "normal" VB files that would be 32767. For
FB files, the largest multiple of the LRECL <= 32767. IIRC, there are some
products which can exceed this. But the QSAM/BSAM access method is stuck at
32767. At least until somebody tells me that I am totally out of date, again.
We code TAPEBLKSZLIM=2G in DEVSUPxx.
I'm not sure if the system uses 128K or 256K blocks for our 3590s when
LBI is used. But, tape block sizes can be much larger than what you've
stated above.
--
Edward E Jaffe
Phoenix Software International, Inc
5200 W Century Blvd, Suite 800
Los Angeles, CA 90045
310-338-0400 x318
[email protected]
http://www.phoenixsoftware.com/
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