[209] in Athena_Backup_System
blank tape design change
daemon@ATHENA.MIT.EDU (Diane Delgado)
Wed Mar 6 13:44:00 1996
To: athena-backup@MIT.EDU
Date: Wed, 06 Mar 1996 13:43:52 EST
From: Diane Delgado <delgado@MIT.EDU>
The current ABS design requires that all tapes be labeled prior to
their being used for a dump operation.
The issue of automatically labeling blank tapes as a part of the dump
operation has been raised by Brian (the current backup system allows
this), and dkk Brian and I have proposed that the ABS be modified to
accomodate automatic labeling of truely blank tapes.
Oh yes, the requirements should probably be modified to reflect this
design change.
Here is the first draft proposal:
There are several kinds of tapes which the ABS can encounter during
a dump operation.
A. Tape with valid ABS Label
B. Tape with no data, and hence no label
C. Tape with no ABS label, but has data
We propose the following handling for each type:
A: slave validates status with master and rejects the tape
(request mount of a new tape) if the tape status is other
than "FREE" (The current implementation supports this).
B: Slave will write a label for this tape and proceed with
dump. => NEW FEATURE <=
C: slave will reject such tapes and request mount of a useable tape.
(The current implementation supports this).
There are a few additional issues for automatic tape labeling:
- we need a way to specify the external label name so that the
information can be entered into the database.
it is possible to add this as part of the dump command interface
for manual dumps.
For dumps which run via the abs schedule we might want to consider
a means which would automatically generate new external label names
based on some pool configuration parameter (e.g. a prefix to which
we append numbers).
Q: is there a better way to tell the ABS what the external label
of the tape is?
We will probably need to add a new service routine to the
ABS_SLAVEINT interface in the master (the interface which handles
slave service requests) to allow the slave to request a newly
generated internal id.
Please give this some thought and provide comments so they can be
incorporated in the detailed design.
Thank U,
dmd
