Minor Change to Read Device Characteristic CCW (x'64')

[arfineman]

In all modern storage controllers a x'64' CCW returns a full word number of cylinders of a volume at offset +60 (x'3C'). This is in addition to a half word at offset +12 (x'0C') and regardless of volume being an EAV or not.

[Fish-Git]

Hi Aaron!

Just so I don't have to go looking for it, is this documented in some manual somewhere?

Thanks!

[arfineman]

Hi Fish,
Look at HCPRDCBK COPY. This causes a problem for the TRACKREAD stage of pipelines. In the case below, TRACKREAD for 100 works, because it is a minidisk and the RDC is filled in by CP. But TRACKREAD fails for 200 because it is a dedicated volume and RDC is taken from the device itself.
Best regards,

/* TRKRD EXEC /
'PIPE TRACKREAD 100 0 0 15' / 100 being any size minidisk /
'PIPE TRACKREAD 200 0 0 15' / 200 being any size attached dasd */

00000C RDCMCYL DS XL2 NUMBER OF PRIMARY CYL
00000E RDCTPCYL DS XL2 NUMBER OF TRACKS PER CYLINDER
000010 RDCSECT DS XL1 NUMBER OF SECTORS
..................................................................................................................................................
00003C RDCMCYL32 DS F NUMBER OF PRIMARY CYLINDERS

[Fish-Git]

Look at HCPRDCBK COPY.

? What the heck is that? That's not a reference manual I've ever heard of. I was looking for something more along the lines of:

• GA32-0099-06 3990 Storage Control Reference (Models 1, 2, and 3)
• GA32-0274-05 3990,9390 Storage Control Reference

Etc...

According to GA32-0274-05 "3990,9390 Storage Control Reference", RDC bytes 12-13 is indeed defined as "Number of Primary cylinders", but bytes 58-63 are defined as "Reserved". I'm looking for a manual that defines those bytes, or something authoritative or even semi-authoritative.

I'm presuming this "HCPRDCBK COPY" thing is some assembler copy book or something? An assembler macro? Where does this "HCPRDCBK COPY" live? In some pds somewhere in z/OS? Or on some minidisk in z/VM somewhere? If so, I would certainly consider that to be authoritative. But with just your word to go on -- no matter how good I personally think it is -- isn't good enough in this case I'm afraid.

(I googled for HCPRDCBK but basically came up dry.)

[Fish-Git]

FOUND IT!

• https://www.vm.ibm.com/pubs/cp720/RDCBK.HTML

003A   58 Bitstring    2 RDC5859        DASD SPECIFIC RESERVED
003C   60 Signed       4 RDCMCYL32      NUMBER OF PRIMARY CYLINDERS

That's good enough for me!  :)

I'll get that fixed for you right away, Aaron. It'll appear in the next release (4.5).

[Fish-Git]

Closed by commit 219956b.