On Nov 28, 2007, at 2:22 PM, Nick Laflamme wrote:

Oh, this is embarrassing. Could someone, perhaps from ADSM
development,
explain Technote 1212111, please? It says explicitly that

   Different generations of media are identified by the trailing 2
   barcode characters of an 8-character external barcode. When only 6
   barcode characters are used, it is not clear what type a media is.

I don't know how many developers remain from ADSM days (:-).

I think the Technote suffers from not having a few more words, in
saying that "not clear" means that it's unclear to the person looking
at the Query LIBVolume output as to the tape type, given that TSM
chooses to report Media Type by media code rather than interpreting
to human language so that it would be immediately understandable.
The technote implicitly suggests that tape type would be clear if the
two identifier characters of the cartridge barcode also participated
in the Volume Name.  That would help, but still would be spartan: the
Media Type column is what really should be expositing this.

My non-authoritative understanding of barcode use is that, as Wanda
says, TSM doesn't use the identifier characters directly, but only as
part of the volume name as they lend uniqueness across media types in
the library.  It is through TSM checkin logic processing that TSM
associates a volume with a device class, and thereafter uses that
associative attribute for proper mounting, etc.  TSM gets 8-character
volume strings through a combination of library settings and device
drivers at an appropriate level, where the string serves as just a
cartridge identity.

Confusion in this area is understandable in the absence of any TSM
writings - per at least my searching - which come right out and say
whether or not TSM uses the two-character type identifier in any
functional way.  We could use a good new or amended Technote to
deliver the gospel.

   Richard Sims