DOKK / manpages / debian 10 / openafs-client / backup_scantape.8.en
BACKUP_SCANTAPE(8) AFS Command Reference BACKUP_SCANTAPE(8)

backup_scantape - Extracts dump information from a tape

backup scantape [-dbadd] [-portoffset <TC port offset>]
[-localauth] [-cell <cell name>] [-help]

backup sc [-d] [-p <TC port offset>] [-l]
[-c <cell name>] [-h]

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.

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.

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).
Specifies the port offset number of the Tape Coordinator handling the tapes for this operation.
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).
Prints the online help for this command. All other valid options are ignored.

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:

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.
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.
The date and time at which the Backup System started performing the dump operation that created the initial dump.
The cell in which the dump set was created. This is the cell whose Backup Database contains a record of the dump set.
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.
The dump level of the initial dump in the dump set.
The dump ID number of the initial dump in the dump set, as recorded in the Backup Database.
The number of times a dump has been written to the tape, or it has been relabeled.

The volume header contains the following fields:

The volume name, complete with a ".backup" or ".readonly" extension, if appropriate.
The volume's volume ID.
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.
The dump ID of the dump named in the "dumpSetName" field.
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.
The dump ID number of "dumpSetName"'s parent dump. It is 0 if the value in the "level" field is 0.
Is always 0; it is reserved for internal use.
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)

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 = example.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

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.

butc(5), backup(8), backup_dump(8), backup_dumpinfo(8), butc(8)

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.

2021-01-27 OpenAFS