SET CAPACITY Command Implemented?

Paul_A_Suhler at Paul_A_Suhler at
Wed Mar 1 12:41:23 PST 2000

* From the T10 Reflector (t10 at, posted by:
* Paul_A_Suhler at
As requested at the February T10/T11.3 Working Group meeting, I reviewed the
spec in search of ways of generating a "short" tape without resorting to the SET
CAPACITY command.  The bottom line is that I could find no non-vendor-unique way
to do this for partitionless media.  Please see "Analysis of SSC Public Review

However, I would not argue with rejecting the SSC public review comment if the
group were to agree that SET CAPACITY should be included in SSC-2 (even though
that is not yet an approved project).  To that end, there is a new copy of the
command description in "SET CAPACITY Command"

One open issue is which opcode to use.  The command was originally proposed with
1Fh.  Ralph Weber recently requested:

   Also, if you do resurrect the SET CAPACITY command, could
   you possibly put it at opcode 0Bh.  Opcode 0Bh currently
   is unused by tapes (but used by disks and printers).
   The original SET CAPACITY opcode choice (1Fh) is the only
   remaining 6-byte CDB opcode that is not used by any
   device types.

To avoid making the choice in a near-vaccuum, I would like to know who has
already implemented this instruction.  We have an implementation in an upcoming
drive and Xyratex claims to generate the command with their tape command
generator.  If there is anyone else, please reply to the reflector or directly
to me and I will bring a count to the meeting next week.

Thanks to all,

Paul Suhler

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