=head1 NAME

backup readlabel - Reads and displays a tape's label

=head1 SYNOPSIS

B<backup readlabel> [-portoffset <I<TC port offset>>]
[B<-localauth>]  [B<-cell> <I<cell name>>]  [B<-help>]

B<backup rea> [B<-p> <I<TC port offset>>]  [B<-l>]  [B<-c> <I<cell name>>]  [-h]

=head1 DESCRIPTION

The backup readlabel command displays information from the
magnetic tape label of a tape. The information includes the tape's
name (either a I<permanent name>, or an I<AFS tape name> that
reflects the tape's contents in a prescribed format) and its
capacity.

If the FILE YES instruction appears in the
B</usr/afs/backup/CFG_>I<device_name> file associated with the
specified port offset, then the B<backup readlabel> command reads the
label information from the first 16 KB block in the backup data file listed
for that port offset in the Tape Coordinator's
B</usr/afs/backup/tapeconfig> file, rather than from the beginning of
a tape.

The Tape Coordinator's default response to this command is to access
the tape by invoking the B<MOUNT> instruction in the local
B</usr/afs/backup/CFG_>I<device_name> file, or by prompting the
backup operator to insert the tape if there is no B<MOUNT>
instruction. However, if the B<AUTOQUERY NO> instruction
appears in the B<CFG_>I<device_name> file, or if the issuer of
the B<butc> command included the B<-noautoquery> flag, the
Tape Coordinator instead expects the tape to be in the device already.
If it is not, the Tape Coordinator invokes the B<MOUNT> instruction or
prompts the operator.

=head1 OPTIONS

=over 4

=item -portoffset

Specifies the port offset number of the Tape Coordinator handling the
tapes for this operation.

=item -localauth

Constructs a server ticket using a key from the local
B</usr/afs/etc/KeyFile> file. The B<backup> command
interpreter presents it to the Backup Server, Volume Server and VL Server
during mutual authentication. Do not combine this flag with the
B<-cell> argument. For more details, see the introductory
B<backup> reference page.

=item -cell

Names the cell in which to run the command. Do not combine this
argument with the B<-localauth> flag. For more details, see the
introductory B<backup> reference page.

=item -help

Prints the online help for this command. All other valid options
are ignored.

=back

=head1 OUTPUT

Output from this command appears in both the shell window where the command
is issued, and in the Tape Coordinator window.

If the tape is unlabeled or if the specified tape device is empty, the
output reads

   Failed to read tape label.

Otherwise, the output in the shell window has the following format:

   Tape read was labelled: I<tape name> (I<dump id>)
        size: I<size> Kbytes

where I<tape name> is the permanent name if the tape has one, or the
AFS tape name otherwise. The I<dump ID> is dump ID of the initial
dump on the tape, and I<size> is the recorded capacity of the tape in
kilobytes.

The output in the Tape Coordinator windows is bounded by an underlined
C<Tape> C<label> header at the top, and the following string
at the bottom:

   -- End of tape label --

In between are lines reporting the following information:

=over 4

=item C<tape name
>

The permanent name assigned by using the -pname argument of the
B<backup labeltape> command. This name remains on the tape
until that argument is used again, no matter how many times the tape is
recycled or otherwise relabeled. If the tape does not have a permanent
name, the value C<<NULL>> appears in this field.

=item C<AFS tape name
>

A tape name in one of the following prescribed formats. The Backup
System automatically writes the appropriate AFS tape name to the label as part
of a B<backup dump> or B<backup savedb> operation, or the
operator can assign it with the B<-name> argument to the B<backup
labeltape> command. 

=over 4

=item *

I<volume_set_name>B<.>I<dump_level_name>.I<tape_index>,
if the tape contains volume data. The I<volume_set_name> is the
name of the volume set that was dumped to create the initial dump in the dump
set of to which this tape belongs; I<dump_level_name> is the last
pathname element of the dump level at which the initial dump was backed
up; and I<tape_index> is the numerical position of the tape in the
dump set.


=item *

C<Ubik.db.dump.>I<tape_index> if the
tape contains a dump of the Backup Database, created with the B<backup
savedb> command. The I<tape_index> is the ordinal of the
tape in the dump set.


=item *

C<<NULL>> if the tape has no AFS tape name. This is
normally the case if the B<-name> argument was not included the last
time the B<backup labeltape> command was used on this tape, and no
data has been written to it since.


=back

=item C<creationTime
>

The date and time at which the Backup System started performing the dump
operation that created the initial dump.

=item C<cell
>

The cell in which the dump set was created. This is the cell whose
Backup Database contains a record of the dump set.

=item C<size
>

The tape's capacity (in kilobytes) as recorded on the label, rather
than the amount of data on the tape. The value is assigned by the
B<-size> argument to the B<backup labeltape> command or
derived from the B</usr/afs/backup/tapeconfig> file on the Tape
Coordinator machine, not from a measurement of the tape.

=item C<dump path
>

The dump level of the initial dump in the dump set

=item C<dump id
>

The dump ID number of the initial dump in the dump set, as recorded in the
Backup Database

=item C<useCount
>

The number of times a dump has been written to the tape, or it has been
relabeled

=back

The message C<ReadLabel: Finished> indicates the completion
of the output.

=head1 EXAMPLES

The following example shows the output for the tape with permanent name
B<oct.guest.dump> and capacity 2 MB, expressed in
kilobyte units (2097152 equals 2 times 10242).

   % backup readlabel -portoffset 6
   Tape read was labelled: oct.guest.dump (907215000)
        size: 2097152 Kbytes

The output in the Tape Coordinator window reads:

   Tape label
   ----------
   tape name = oct.guest.dump
   AFS tape name = guests.monthly.3
   creationTime = Thu Oct 1 00:10:00 1998
   cell = abc.com
   size = 2097152 Kbytes
   dump path = /monthly
   dump id = 907215000
   useCount = 5
   ---- End of tape label ----

The following example is for a tape that does not have a permanent
tape.

   % backup readlabel -portoffset 6
   Tape read was labelled: guests.monthly.2 (909899900)
        size: 2097152 Kbytes

The output in the Tape Coordinator window reads:

   Tape label
   ----------
   tape name = <NULL>
   AFS tape name = guests.monthly.2
   creationTime = Sun Nov 1 00:58:20 1998
   cell = abc.com
   size = 2097152 Kbytes
   dump path = /monthly
   dump id = 909899900
   useCount = 1
   ---- End of tape label ----

=head1 PRIVILEGE REQUIRED

The issuer must be listed in the /usr/afs/etc/UserList file on
every machine where the Backup Server is running, or must be logged onto a
server machine as the local superuser B<root> if the
B<-localauth> flag is included.

=head1 SEE ALSO

L<backup(1)>,
L<backup_labeltape(1)>,
L<butc(1)>

=head1 COPYRIGHT

IBM Corporation 2000. <http://www.ibm.com/> All Rights Reserved.

This documentation is covered by the IBM Public License Version 1.0.  It was
converted from HTML to POD by software written by Chas Williams and Russ
Allbery, based on work by Alf Wachsmann and Elizabeth Cassell.