|BACKUP_VOLSETRESTORE(8)||AFS Command Reference||BACKUP_VOLSETRESTORE(8)|
backup_volsetrestore - Restores all volumes in a volume set
[-name <volume set name>]
[-file <file name>]
[-portoffset <TC port offset>+]
[-extension <new volume name extension>] [-dryrun | -n]
[-localauth] [-cell <cell name>] [-help]
[-na <volume set name>]
[-f <file name>]
[-p <TC port offset>+]
[-e <new volume name extension>]
[-dryrun | -n] [-l] [-c <cell name>] [-h]
The backup volsetrestore command restores the complete contents of a group of read/write volumes to the file system, by restoring data from the last full dump and all subsequent incremental dumps of each volume. It is most useful for recovering from loss of data on multiple partitions, since it can restore each of a defined set of volumes to a different site.
(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 volsetrestore command restores data from the backup data file listed for that port offset in the Tape Coordinator's /var/lib/openafs/backup/tapeconfig file, instead of from 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 restoring one or more volumes to a single site only, it is usually more efficient to use the backup volrestore command. If restoring all volumes that resided on a single partition, it is usually more efficient to use the backup diskrestore command.
Indicate the volumes to restore by providing either the -name argument or the -file argument:
- The -name argument names a volume set. The Backup System restores
all volumes listed in the Volume Location Database (VLDB) that match the
server, partition, and volume name criteria defined in the volume set's
volume entries, and for which dumps are available. It restores the volumes
to their current site (machine and partition), and by default overwrites
the existing volume contents.
It is not required that the volume set was previously used to back up volumes (was used as the -volumeset option to the backup dump command). It can be defined especially to match the volumes that need to be restored with this command, and that is usually the better choice. Indeed, a temporary volume set, created by including the -temporary flag to the backup addvolset command, can be especially useful in this context. A temporary volume set is not added to the Backup Database and exists only during the current interactive backup session, which is suitable if the volume set is needed only to complete the single restore operation initialized by this command.
The reason that a specially defined volume set is probably better is that volume sets previously defined for use in dump operations usually match the backup version of volumes, whereas for a restore operation it is best to define volume entries that match the base (read/write) name. In that case, the Backup System searches the Backup Database for the newest dump set that includes either the read/write or the backup version of the volume. If, in contrast, a volume entry explicitly matches the volume's backup or read-only version, the Backup System restores dumps of that volume version only.
- The -file argument names a file that lists specific volumes and the site to which to restore each. The volume name must match the name used in Backup Database dump records rather than in the VLDB, if they differ, because the Backup System does not look up volumes in the VLDB. The specified site can be different than the volume's current one; in that case, the Backup System removes the current version of the volume and updates the volume's location information in the VLDB.
If all of the full and incremental dumps of all relevant volumes were not written to a type of tape that a single Tape Coordinator can read, use the -portoffset argument to list multiple port offset numbers in the order in which the tapes are needed (first list the port offset for the full dump, second the port offset for the level 1 incremental dump, and so on). This implies that the full dumps of all relevant volumes must have been written to a type of tape that the first Tape Coordinator can read, the level 1 incremental dumps to a type of tape the second Tape Coordinator can read, and so on. If dumps are on multiple incompatible tape types, use the backup volrestore command to restore individual volumes, or use this command after defining new volume sets that group together volumes that were dumped to compatible tape types. For further discussion, see the OpenAFS Administration Guide.
By default, the Backup System overwrites the contents of an existing volume with the restored data. To create a new volume to house the restored version instead, use the -extension argument. The Backup System derives the new volume's name by adding the specified extension to the read/write base name, and creates a new VLDB entry. The command does not affect the existing volume in any way. However, if a volume with the specified extension also already exists, the command overwrites it.
The -dryrun flag produces a list of the volumes to be restored if the -dryrun flag were not included, without actually restoring any volumes. See "OUTPUT" for a detailed description of the output, and suggestions on how to combine it most effectively with the -file and -name arguments.
The execution time for a backup volsetrestore command depends on the number of volumes to be restored and the amount of data in them, but it can take hours to restore a large number of volumes. One way to reduce the time is to run multiple instances of the command simultaneously, either using the -name argument to specify disjoint volume sets for each command, or the -file argument to name files that list different volumes. This is possible if there are multiple available Tape Coordinators that can read the required tapes. Depending on how the volumes to be restored were dumped to tape, specifying disjoint volume sets can also reduce the number of tape changes required.
The Tape Coordinator's default response to this command is to access the first tape it needs by invoking the "MOUNT" instruction in the local /var/lib/openafs/backup/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, or is the wrong tape, the Tape Coordinator invokes the "MOUNT" instruction or prompts the operator. It also invokes the "MOUNT" instruction or prompts for any additional tapes needed to complete the restore operation; the backup operator must arrange to provide them.
- -name <volume set name>
- Names a volume set to restore. The Backup System restores all of the volumes listed in the VLDB that match the volume set's volume entries. Provide this argument or the -file argument, but not both.
- -file <file name>
- Specifies the full pathname of a file that lists one or more volumes and
the site (file server machine and partition) to which to restore each. Use
either this argument or the -name argument, but not both.
Each volume's entry must appear on its own (unbroken) line in the file, and have the following format:
<machine> <partition> <volume> [<comments> ...]
- Names the file server machine to which to restore the volume.
- Names the partition to which to restore the volume.
- Names the volume to restore. It is generally best to specify the base (read/write) name of each volume. In this case, the Backup System searches the Backup Database for the newest dump set that includes a dump of either the read/write or the backup version of the volume. It restores the dumps of that version of the volume, starting with the most recent full dump. If, in contrast, the name explicitly includes the ".backup" or ".readonly" extension, the Backup System restores dumps of that volume version only.
- <comments> ...
- Is any other text. The Backup System ignores any text on each line that appears after the volume name, so this field can be used for notes helpful to the backup operator or other administrator.
Do not use wildcards (for example, ".*") in the <machine>, <partition>, or <volume> fields. It is acceptable for multiple lines in the file to name the same volume, but the Backup System processes only the first of them.
- -extension <new volume name extension>
- Creates a new volume for each volume specified by the -name or -file argument, to house the restored data from that volume. The Backup System derives the new volume's name by appending the specified string to the read/write base name, and creates a new VLDB volume entry. It preserves the contents of each existing volume. Any string other than ".readonly" or ".backup" is acceptable, but the combination of the base name and extension cannot exceed 22 characters in length. To use a period to separate the extension from the name, specify it as the first character of the string (as in ".rst", for example).
- -portoffset <TC port offset>+
- Specifies one or more port offset numbers (up to a maximum of 128), each
corresponding to a Tape Coordinator to use in the operation. If there is
more than one value, the Backup System uses the first one when restoring
the full dump of each volume, the second one when restoring the level 1
incremental dump of each volume, and so on. It uses the final value in the
list when restoring dumps at the corresponding depth in the dump hierarchy
and all dumps at lower levels.
Provide this argument unless the default value of 0 (zero) is appropriate for all dumps. If 0 is just one of the values in the list, provide it explicitly in the appropriate order.
- -dryrun | -n
- Displays a list of the volumes to be restored if the flag were not included, without actually restoring them. "OUTPUT" details the format of the output. When combined with the -name argument, its output is easily edited for use as input to the -file argument on a subsequent backup volsetrestore command.
- 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.
If the -dryrun flag is not provided, the command displays a unique task ID number for the operation, in two places:
- In the shell window, directly following the command line.
- In the Tape Coordinator window, if the butc process was started at debug level 1.
The task ID number is not the same as the job ID number displayed by the backup jobs command when the backup volsetrestore command is issued in interactive mode. The Backup System does not assign either type of ID number until the restoration process actually begins.
When the -dryrun flag is included, no task ID or job ID numbers are reported because none are assigned. Instead, the output begins with a count of the number of volumes to be restored, followed by a line for each dump of a volume. For each volume, the line representing the most recent full dump appears first, and lines for any subsequent incremental dumps follow, ordered by dump level. The lines for a given volume do not necessarily appear all together, however.
The format of each line is as follows (the output is shown here on two lines only for legibility reasons):
<machine> <partition> <volume_dumped> # as <volume_restored>; \ <tape_name> (<tape_ID>); pos <position_number>; <date>
- Names the file server machine that currently houses the volume, as listed in the VLDB.
- Names the partition that currently houses the volume, as listed in the VLDB.
- Specifies the version (read/write or backup) of the volume that was dumped, as listed in the Backup Database.
- Specifies the name under which to restore the volume. The Backup System only restores data to read/write volumes. If the -extension argument is included, then the specified extension appears on the name in this field (for example, "user.pat.rst").
- Names the tape containing the dump of the volume, from the Backup Database. If the tape has a permanent name, it appears here; otherwise, it is the AFS tape name.
- The tape ID of the tape containing the dump of the volume, from the Backup Database.
- Specifies the dump's position on the tape (for example, 31 indicates that 30 volume dumps precede the current one on the tape). If the dump was written to a backup data file, this number is the ordinal of the 16 KB-offset at which the volume's data begins.
- The date and time when the volume was dumped.
One way to generate a file for use as input to the -file argument is to combine the -name and -dryrun options, directing the output to a file. The OpenAFS Administration Guide section on using the Backup System to restore data explains how to edit the file as necessary before using it as input to the -file argument.
The output of this command includes only volumes for which the Backup Database includes at least one dump record. The command interpreter generates a message on the standard error stream about volumes that do not have dump records but either are listed in the file named by the -file argument, or appear in the VLDB as a match to a volume entry in the volume set named by the -name argument.
The following command restores all volumes included in entries in the volume set named "data.restore", which was created expressly to restore data to a pair of file server machines on which all data was corrupted due to a software error. All volumes are restored to the sites recorded in their entries in the VLDB.
% backup volsetrestore -name data.restore Starting restore backup: task ID of restore operation: 112 backup: Finished doing restore
The following command restores all volumes that have entries in the file named /tmp/restore:
% backup volsetrestore -file /tmp/restore Starting restore backup: task ID of restore operation: 113 backup: Finished doing restore
The /tmp/restore file has the following contents:
fs1.example.com b user.pat fs1.example.com b user.terry fs1.example.com b user.smith fs2.example.com c user.jones . . . . . .
The issuer must be listed in the /etc/openafs/server/UserList file on every machine where the Backup Server or Volume Location (VL) Server is running, and on every file server machine that houses an affected volume. If the -localauth flag is included, the issuer must instead be logged on to a server machine as the local superuser "root".
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