On Thu, Apr 18, 2002 at 10:44:39AM -0500, Rick Troth wrote:
> And what will happen now with SCSI attachment to zSeries?
> I can only hope that there will NOT be some CKD protocol.
> It just doesn't seem worth it when FBA is what is really happening.

Probably so, at least for VM, VSE, and Linux.

> With CKD,  Linux must play the C/H/S game.
> With emulated CKD,  so must the DASD subsystem.
> Why not let both ends stop faking it??

Mainframers - at least MVS types - aren't used to thinking that way. A sile
as a stream of bytes is completely alien to them.

> But VSE and VM both work with FBA DASD.

VM has always used a fixed-block structured filesystem internally anyway, so
it was just a matter of changing block sizes. I can't speak to VSE, never
having dealt with it.

> I'm not saying that we should endorse FBA to the demise of MVS.
> I am only saying that we should endorse FBA to the benefit of
> Linux, VM, and VSE.   And with modern DASD subsystems,
> it should be no great pain to present either flavor as needed.
> Let MVS have its CKD.   But let the rest have FBA when they want.

I believe that's the case now.

There's one benefit for Hercules users of using CKD instead of FBA:
compressed DASD images. Compressed CKD is a big win. Unfortunately, there's
no compressed FBA support.

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