Bruce Black wrote:
The Encryption Facility can use HW-based compression before
encryption, all on the server. (One has to specify its use because
there is no way to uncompress the data on a non-z server.)
??? the hardware compression (CPACF) has been available on all systems
for many years and generations, long before zSeries. I am sure it is
available on any system which is still in use. Even if it wasn't there,
the op system contains software emulation (at a CPU price, of course).
I think the main reason that compression is optional is for data that is
already compressed or naturally incompressible; compress CPU time goes
up on such data as it tries to find ways to compress it
You're correct that hardware compression has been around for some
time (though the CPACF is for encryption, not compression, and
it's relatively new). But although pre-System z servers
certainly do support compression, the Encryption Facility for
z/OS requires an IBM System z server (of which zSeries servers
are a proper subset).
In any case, what I was trying to say is that the Encryption
Facility for z/OS requires that you specify compression if you
want the data to be compressed. This choice was made because the
Java-based Encryption Facility Client (which can run wherever
Java runs) does not support uncompressing the data that has been
compressed on a server.
--
John Eells
z/OS Technical Marketing
IBM Poughkeepsie
[EMAIL PROTECTED]
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