[Info-vax] ISAM on disk layout. Was: Re: HP wins Oracle Itanium case

[Nomen Nescio]

Jan-Erik Soderholm <jan-erik.soderholm at telia.com> wrote:

> Even more so in todays SAN's where you get a number of "gigs"
> out of some undefined disk array. Placement of files, as in
> MVS and other older systems, is mostly an non-issue today,

It's a non issue today on MVS as well and has been for most of its
history. Does anybody know if VSE still needs it?

> from a performance standpoint. The fact that MVS still needs
> BLOCKSIZE, LRECL and so on, is mostly a compatibility issue.

Really those are much more than just for compatibility. There are still
millions of programs reading and writing SAM (not much ISAM, but BSAM and
QSAM) and it helps the access method block and deliver the data. Either the
program or the DCB has to have the information, or things will not work.