[72] in Athena_Backup_System
Tape layout
daemon@ATHENA.MIT.EDU (Jonathon Weiss)
Wed Feb 8 20:17:07 1995
From: Jonathon Weiss <jweiss@MIT.EDU>
To: athena-backup@MIT.EDU
Date: Wed, 08 Feb 1995 20:16:30 EST
Please take a look at this before the meeting...
Jonathon
Here's what I am currently planning to have the tape layout look like.
Tape label: I've looked at the the Tape Label struct that the AFS
backup uses, and I am not going to use it. It contains a lot of data
that we will be storing on the master, and doesn't need to be stored
on the tape itself. It is also missing Several fields that we need.
I'm proposing the following structure as teh tape header.
abs_tape_header{
int magic; /* Try to confirm that things aren't corrupt */
char name[256]; /* Name of the ABS domain */
int pool; /* The ABS pool */
int external_id; /* The ABS ID printed on the tape */
int internal_id; /* The ABS ID only known to the system */
int timestamp; /* UNIX timestamp of the date the last write operation began */
};
If you know what I forgot to include in this struct, please let me knoe. :-)
I plan to have filemarks on the tape after the tape header, and after
each volume. Diane, can you confirm that this isn't gratutiously
different than what the AFS backups currently do? I wasn't sure I
completely understood one of the comments in the volume header
structure. It made it sound like there might be a filemark between
the volume header and the volume, but I don't think so. Anyhow we
probably want to do whatever AFS does in this case.
I'm still looking at the volume header structure. I'm hoping we can
take the AFS struct wholesale for consistancy, but I'm not sure we
won't need additional fields in the structure.
