Rick wrote:

"Another datapoint indicating that MVS should learn
FBA. But it's a losing battle.   There seems to be
some unwritten law that says "disk" on "channel" must
be [E]CKD,  so that while VM, VSE, Linux, and others
are happily embracing fixed block disk, the mainframe
channel-attached "disk" MARKET stays constrained."

Actually, it is a well know economic law. If people
don't buy it, why support it?

When os/370 came out, it introduced a fixed block file
system (VSAM) now standardized at 4K blocks, eerily
similar to the block size of a page in memory and the
page size on disk. Also introduced were fixed block
devices that would handle both VSAM and paging nicely.

Few people bought them because most of their data were
in odd size blocks, mostly multiples of 80 and they
didn't want to have a mix of devices - some for VSAM
and paging and some for the rest of their data. And to
this day, a good portion of the data of the people who
buy zSeries day are bound by the 80 byte record and
variable sized blocks.

Its pretty much the same reason people buy 2x4's
(boards). That's a standard and its been around a very
long time, so housing and building construction is
based on a standard wood 2x4, even if the material is
steel! A hollow steel 2x4 is stronger than a solid
wood 2x4, but the measurement is still a 2x4!


=====
Jim Sibley
RHCT, Implementor of Linux on zSeries

"Computer are useless.They can only give answers." Pablo Picasso

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