NAME
backup_scantape - Extracts dump information from a tape
SYNOPSIS
backup scantape [-dbadd] [-portoffset <TC port offset>]
[-localauth] [-cell <cell name>] [-help]
backup sc [-d] [-p <TC port offset>] [-l]
[-c <cell name>] [-h]
DESCRIPTION
The backup scantape command extracts information from the dump labels
and volume headers on the tape in the device controlled by the Tape
Coordinator indicated by the -portoffset argument. The Tape Coordinator
displays the information for each volume in its window as soon as it
extracts it (rather than waiting until it has scanned the entire tape).
(If the "FILE YES" instruction appears in the
/var/lib/openafs/backup/CFG_device_name file associated with the
specified port offset, then the backup scantape command extracts dump
information from the backup data file named in that port offset’s entry
in the /var/lib/openafs/backup/tapeconfig file on the Tape Coordinator
machine, rather than from a tape. For the sake of clarity, the
following text refers to tapes only, but the Backup System handles
backup data files in much the same way.)
If the -dbadd flag is provided, the backup scantape command creates new
dump and volume records in the Backup Database for the scanned
information. However, if it finds that a record already exists in the
database for the same dump, it terminates the scanning operation.
The scanning operation works only on tapes containing volume data. The
command fails with an error message if the tape contains a copy of the
Backup Database (was created with the backup savedb command, or has the
AFS tape name "Ubik_db_dump.1").
The Tape Coordinator’s default response to this command is to access
the tape by invoking the "MOUNT" instruction in the CFG_device_name
file, or by prompting the backup operator to insert the tape if there
is no "MOUNT" instruction. However, if the "AUTOQUERY NO" instruction
appears in the CFG_device_name file, or if the issuer of the butc
command included the -noautoquery flag, the Tape Coordinator instead
expects the tape to be in the device already. If it is not, the Tape
Coordinator invokes the "MOUNT" instruction or prompts the operator.
To terminate a tape scanning operation in interactive mode, issue the
backup kill command. In noninteractive mode, the only choice is to use
a termination signal such as Ctrl-C to halt the Tape Coordinator
completely.
CAUTIONS
A scanning operation does not have to begin with the first tape in a
dump set, but the Backup System can process tapes only in sequential
order after the initial tape provided. The Tape Coordinator
automatically requests any subsequent tapes by invoking the "MOUNT"
instruction in the local /var/lib/openafs/backup/CFG_device_name file,
or by prompting the operator if there is no "MOUNT" instruction.
The Tape Coordinator’s success in scanning a tape that is corrupted or
damaged depends on the extent of the damage and what type of data is
corrupted. It can almost always scan the tape successfully up to the
point of damage. If the damage is minor, the Tape Coordinator can
usually skip over it and scan the rest of the tape, but more major
damage can prevent further scanning. Because a scanning operation can
start on any tape in a dump set, damage on one tape does not prevent
scanning of the others in the dump set. However, it is possible to scan
either the tapes that precede the damaged one or the ones that follow
it, but not both.
If a tape is relabeled with the backup labeltape command, it is not
possible to recover data from it for the purposes of rebuilding the
Backup Database.
If the -dbadd flag is included on the command, it is best not to
terminate the tape scanning operation before it completes (for example,
by issuing the backup kill command in interactive mode). The Backup
System writes a new record in the Backup Database for each dump as soon
as it scans the relevant information on the tape, and so it possibly
has already written new records. If the operator wants to rerun the
scanning operation, he or she must locate and remove the records
created during the terminated operation: the second operation exits
automatically if it finds that a record that it needs to create already
exists.
If the -dbadd flag is included and the first tape provided is not the
first tape in the dump set, the following restrictions apply:
· If the first data on the tape is a continuation of a volume that
begins on the previous (unscanned) tape in the dump set, the Backup
System does not add a record for that volume to the Backup
Database.
· The Backup System must read the marker that indicates the start of
an appended dump to add database records for the volumes in it. If
the first volume on the tape belongs to an appended dump, but is
not immediately preceded by the appended-dump marker, the Backup
System does not create a Backup Database record for it or any
subsequent volumes that belong to that appended dump.
OPTIONS
-dbadd
Adds the information extracted from the tape to the Backup Database
(but only if the database does not already contain an entry with
the same dump ID number).
-portoffset <TC port offset>
Specifies the port offset number of the Tape Coordinator handling
the tapes for this operation.
-localauth
Constructs a server ticket using a key from the local
/etc/openafs/server/KeyFile file. The backup command interpreter
presents it to the Backup Server, Volume Server and VL Server
during mutual authentication. Do not combine this flag with the
-cell argument. For more details, see backup(8).
-cell <cell name>
Names the cell in which to run the command. Do not combine this
argument with the -localauth flag. For more details, see backup(8).
-help
Prints the online help for this command. All other valid options
are ignored.
OUTPUT
For every dump on a tape, the backup scantape command displays in the
Tape Coordinator window the dump label and the volume header of each
volume in the dump. If a dump spans more than one tape, the dump label
does not repeat at the beginning of subsequent tapes.
A dump label contains the following fields, which are the same as in
the output from the backup readlabel command:
tape name
The permanent name assigned by using the -pname argument of the
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 "<NULL>" appears in this field.
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 backup dump operation, or the operator can
assign it with the -name argument to the backup labeltape command.
· volume_set_name.dump_level_name.tape_index, if the tape
contains volume data. The volume_set_name is the name of the
volume set that was dumped to create the initial dump in the
dump set of which this tape is a part; dump_level_name is the
last pathname element of the dump level at which the initial
dump was backed up; and tape_index is the numerical position of
the tape in the dump set.
· "<NULL>" if the tape has no AFS tape name. This is normally the
case if the -name argument was not included the last time the
backup labeltape command was used on this tape, and no data has
been written to it since.
creationTime
The date and time at which the Backup System started performing the
dump operation that created the initial dump.
cell
The cell in which the dump set was created. This is the cell whose
Backup Database contains a record of the dump set.
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
-size argument to the backup labeltape command or derived from the
/var/lib/openafs/backup/tapeconfig file on the Tape Coordinator
machine, not from a measurement of the tape.
dump path
The dump level of the initial dump in the dump set.
dump id
The dump ID number of the initial dump in the dump set, as recorded
in the Backup Database.
useCount
The number of times a dump has been written to the tape, or it has
been relabeled.
The volume header contains the following fields:
volume name
The volume name, complete with a ".backup" or ".readonly"
extension, if appropriate.
volume ID
The volume’s volume ID.
dumpSetName
The dump to which the volume belongs. The dump name is of the form
volume_set_name.dump_level_name and matches the name displayed in
the dump label.
dumpID
The dump ID of the dump named in the "dumpSetName" field.
level
The depth in the dump hierarchy of the dump level used in creating
the dump. A value of 0 indicates a full dump. A value of 1 or
greater indicates an incremental dump made at the indicated depth
in the hierarchy. The value reported is for the entire dump, not
necessarily for the volume itself; for example, it is possible for
a dump performed at an incremental level to include a full dump of
an individual volume if the volume was omitted from previous dumps.
parentID
The dump ID number of "dumpSetName"’s parent dump. It is 0 if the
value in the "level" field is 0.
endTime
Is always 0; it is reserved for internal use.
cloneDate
The date and time at which the volume was created. For a backup or
read-only volume, this represents the time at which it was cloned
from its read/write source. For a read/write volume, it indicates
the time at which the Backup System locked the volume for purposes
of including it in the dump named in the "dumpSetName" field.
The message "Scantape: Finished" indicates the completion of the
output.
In normal circumstances, the Backup System writes a marker to indicate
that a volume is the last one on a tape, or that the volume continues
on the next tape. However, if a backup operation terminated abnormally
(for example, because the operator terminated the Tape Coordinator by
issuing the Ctrl-C command during the operation), then there is no such
marker. Some very early versions of the Backup System also did not
write these markers. If a tape does not conclude with one of the
expected markers, the Tape Coordinator cannot determine if there is a
subsequent tape in the dump set and so generates the following message
in its window:
Are there more tapes? (y/n)
EXAMPLES
The following example shows the output for the first two volumes on a
tape in the device with port offset 0:
% backup scantape
Dump label
----------
tape name = monthly_guest
AFS tape name = guests.monthly.3
creationTime = Mon Feb 1 04:06:40 1999
cell = abc.com
size = 2150000 Kbytes
dump path = /monthly
dump id = 917860000
useCount = 44
-- End of dump label --
-- volume --
volume name: user.guest10.backup
volume ID 1937573829
dumpSetName: guests.monthly
dumpID 917860000
level 0
parentID 0
endTime 0
clonedate Mon Feb 1 03:03:23 1999
-- volume --
volume name: user.guest11.backup
volume ID 1938519386
dumpSetName: guests.monthly
dumpID 917860000
level 0
parentID 0
endTime 0
clonedate Mon Feb 1 03:05:15 1999
PRIVILEGE REQUIRED
The issuer must be listed in the /etc/openafs/server/UserList file on
every machine where the Backup Server is running, or must be logged
onto a server machine as the local superuser "root" if the -localauth
flag is included.
SEE ALSO
butc(5), backup(8), backup_dump(8), backup_dumpinfo(8), butc(8)
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.