Discussion:
Format of FBA dasd VOL1 label
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'\'Fish\' (David B. Trout)' david.b.trout@gmail.com [hercules-390]
2018-05-21 19:22:58 UTC
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I'm trying to code a small function that constructs a dasd VOL1 label and already know what it looks like for CKD, but I'm a little unclear as to what it should look like for FBA dasd.

I found a web page at IBM that describes the VOL1 label:

<https://www.ibm.com/support/knowledgecenter/en/SSB27H_6.2.0/fa2mr_app_c_volume_label_on_disk.html>

but it's unclear to me as to what the actual format is for some of the fields. For example, the VTOC address is binary CCHHR for CKD, but for FBA should it be binary 00BBBBBBBB or BBBBBBBB00? If the block number of the VTOC is block number 2 (typical), then should it be X'0000000002' or X'0000000200'? (i.e. should the first byte be the binary zero or the last byte? I'm guessing the first byte, thus X'0000000002', but I'm not sure.

Also, I seem to recall seeing some numeric fields in a HDR1 label being character numeric and not binary, so I'm also a little unclear as how the CI-size, blocks per CI and labels per CI field fields should be formatted. Should they be character "1024", "0004" and "0056" respectively? Or should they be X'00000400', X'00000004' and X'00000038' binary?

If someone has access to a real FBA drive at their shop I'd really appreciate seeing a hex dump of block number 1 of the drive!

Thanks!
--
"Fish" (David B. Trout)
Software Development Laboratories
http://www.softdevlabs.com
mail: ***@softdevlabs.com
Peter Coghlan mailinglists@beyondthepale.ie [hercules-390]
1970-01-01 00:00:00 UTC
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Post by '\'Fish\' (David B. Trout)' ***@gmail.com [hercules-390]
I'm trying to code a small function that constructs a dasd VOL1 label and already know what it looks like for CKD, but I'm a little unclear as to what it should look like for FBA dasd.
<https://www.ibm.com/support/knowledgecenter/en/SSB27H_6.2.0/fa2mr_app_c_volume_label_on_disk.html>
but it's unclear to me as to what the actual format is for some of the fields. For example, the VTOC address is binary CCHHR for CKD, but for FBA should it be binary 00BBBBBBBB or BBBBBBBB00? If the block number of the VTOC is block number 2 (typical), then should it be X'0000000002' or X'0000000200'? (i.e. should the first byte be the binary zero or the last byte? I'm guessing the first byte, thus X'0000000002', but I'm not sure.
Also, I seem to recall seeing some numeric fields in a HDR1 label being char acter numeric and not binary, so I'm also a little unclear as how the CI-size, blocks per CI and labels per CI field fields should be formatted. Should they be character "1024", "0004" and "0056" respectively? Or should they be X'00000400', X'00000004' and X'00000038' binary?
If someone has access to a real FBA drive at their shop I'd really appreciate seeing a hex dump of block number 1 of the drive!
Hi Fish,

The MUSIC/SP demo system comes on an FBA volume. It can be found here:

http://www.canpub.com/teammpg/de/mcgweb/downloads.htm

One way to look at it would be to ipl it in Hercules and use the MUSIC DSKDMP
command.

Regards,
Peter Coghlan.
'\'Fish\' (David B. Trout)' david.b.trout@gmail.com [hercules-390]
2018-05-22 02:35:05 UTC
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Peter Coghlan wrote:

[...]
The MUSIC/SP demo system comes on an FBA volume. [...]
Thanks Peter!

Harold Grovesteen had already sent me a document that provided all the information I was needing an more, but I went ahead and downloaded the MUSIC demo anyway to verify it matches what Harold sent me, and it does.

Thanks again.

PROBLEM RESOLVED, folks. So if anyone else is tempted to respond there is no longer any need. I have my answer.

Thank you Peter and thank you *especially* to Harold.
--
"Fish" (David B. Trout)
Software Development Laboratories
http://www.softdevlabs.com
mail: ***@softdevlabs.com
'\'Fish\' (David B. Trout)' david.b.trout@gmail.com [hercules-390]
2018-05-21 19:38:11 UTC
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[...]
Should they be character "1024", "0004" and "0056"...
Or should they be X'00000400', X'00000004' and ...
Wow. I can't even do simple math! Sorry!

The block-per-CI field (for a CI-size of 1024 bytes) should of course be "0002" (or X'00000002'), not 4! (Duh!) Sorry. :(

I'd still very much like to see a hex dump, but if someone out there actually KNOWS for sure what the fields should actually look like for FBA, I'd *really* appreciate them passing that information on!

Thanks.
--
"Fish" (David B. Trout)
Software Development Laboratories
http://www.softdevlabs.com
mail: ***@softdevlabs.com
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