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backup

Section: AFS Command Reference (8)
Updated: OpenAFS
Index 

NAME

backup - Introduction to the backup command suite 

DESCRIPTION

The commands in the backup command suite are the administrativeinterface to the AFS Backup System. There are several categories ofcommands in the suite:
*
Commands to copy data from AFS volumes to tape or a backup data file, andto restore it to the file system: backup diskrestore, backup dump,backup volrestore, and backup volsetrestore.
*
Commands to administer the records in the Backup Database: backupadddump, backup addhost, backup addvolentry, backup addvolset,backup deldump, backup deletedump, backup delhost, backupdelvolentry, backup delvolset, backup dumpinfo, backuplistdumps, backup listhosts, backup listvolsets, backupscantape, backup setexp, and backup volinfo.
*
Commands to write and read tape labels: backup labeltape and backupreadlabel.
*
Commands to list and change the status of backup operations and themachines performing them: backup jobs, backup kill, and backupstatus.
*
Commands to enter and leave interactive mode: backup interactive andbackup quit.
*
Commands to check for and repair corruption in the Backup Database:backup dbverify, backup restoredb, and backup savedb.
*
Commands to obtain help: backup apropos and backup help.

The backup command interpreter interacts with two other processes:

*
The Backup Server (buserver) process. It maintains the Backup Database,which stores most of the administrative information used by the BackupSystem. In the standard configuration, the Backup Server runs on eachdatabase server machine in the cell, and uses AFS's distributed databasetechnology, Ubik, to synchronize its copy of the database with the copieson the other database server machines.
*
The Backup Tape Coordinator (butc) process. A separate instance of theprocess controls each tape device or backup data file used to dump orrestore data. The Tape Coordinator runs on a Tape Coordinator machine,which is an AFS server or client machine that has one or more tape devicesattached, or has sufficient disk space to accommodate one or more backupdata files on its local disk.

Each Tape Coordinator must be registered in the Backup Database and in the/usr/afs/backup/tapeconfig configuration file on the Tape Coordinatormachine's local disk, and information in the two places must be consistentfor proper Backup System performance. The optional/usr/afs/backup/CFG_device_name for each Tape Coordinator recordsinformation used to automate its operation.

In addition to the standard command line interface, the backup commandsuite provides an interactive interface, which has several usefulfeatures described in the backup_interactive(8) manpage. Three of the commands inthe suite are available only in interactive mode: backup jobs, backupkill, and backup quit. 

OPTIONS

The following options are available on many commands in the backupsuite. The reference page for each command also lists them, but they aredescribed here in greater detail.
-cell <cell name>
Names the cell in which to run the command. It is acceptable to abbreviatethe cell name to the shortest form that distinguishes it from the otherentries in the /usr/vice/etc/CellServDB file on the local machine. Ifthe -cell argument is omitted, the command interpreter determines thename of the local cell by reading the following in order:
*
The value of the AFSCELL environment variable.
*
The local /usr/vice/etc/ThisCell file.

Do not combine the -cell and -localauth options. A command on whichthe -localauth flag is included always runs in the local cell (asdefined in the server machine's local /usr/afs/etc/ThisCell file),whereas a command on which the -cell argument is included runs in thespecified foreign cell.

The -cell argument is not available on commands issued in interactivemode. The cell defined when the backup command interpreter entersinteractive mode applies to all commands issued during the interactivesession.

-help
Prints a command's online help message on the standard output stream. Donot combine this flag with any of the command's other options; when it isprovided, the command interpreter ignores all other options, and onlyprints the help message.
-localauth
Constructs a server ticket using the server encryption key with thehighest key version number in the local /usr/afs/etc/KeyFile file. Thebackup command interpreter presents the ticket, which never expires, tothe Backup Server, Volume Server and Volume Location (VL) Server duringmutual authentication.

Use this flag only when issuing a command on a server machine; clientmachines do not usually have a /usr/afs/etc/KeyFile file. The issuerof a command that includes this flag must be logged on to the servermachine as the local superuser root. The flag is useful for commandsinvoked by an unattended application program, such as a process controlledby the UNIX cron utility or by a cron entry in the machine's/usr/afs/local/BosConfig file. It is also useful if an administrator isunable to authenticate to AFS but is logged in as the local superuserroot.

Do not combine the -cell and -localauth options. A command on whichthe -localauth flag is included always runs in the local cell (asdefined in the server machine's local /usr/afs/etc/ThisCell file),whereas a command on which the -cell argument is included runs in thespecified foreign cell.

The -localauth argument is not available on commands issued ininteractive mode. The local identity and AFS tokens with which thebackup command interpreter enters interactive mode apply to allcommands issued during the interactive session.

-portoffset <TC port offset>
Specifies the port offset number of the Tape Coordinator that is toexecute the backup command. The port offset number uniquely identifiesa pairing of a Tape Coordinator (butc) process and tape device orbackup data file.

The backup command interpreter and Tape Coordinator process communicatevia a UDP socket, or port. Before issuing a backup command thatinvolves reading or writing a tape, the backup operator must start abutc process that controls the appropriate tape device and listens forrequests sent to its port number. If a Backup System machine has multipletape devices attached, they can perform backup operations simultaneouslybecause each device has its own associated butc process and port offsetnumber.

The Backup System associates a tape capacity and file mark size with eachport offset (as defined in the tapeconfig file). For a compressing tapedevice, the capacity and file mark values differ for compression andnon-compression modes, so the two modes have distinct port offset numbers.

The Backup Database can store up to 58,511 port offsets, so the legalvalues for this argument are the integers 0 through 58510. If theissuer omits the argument, it defaults to 0. (The limit of 58,511 portoffsets results from the fact that UDP socket numbers are identified by a16-bit integer, and the lowest socket number used by the Backup System is7025. The largest number that a 16-bit integer can represent is65,535. Subtracting 7,025 yields 58,510. The addition of port offset 0(zero) increases the maximum to 58,511.)

Although it is possible to define up to 58,511 port offset numbers for acell, it is not possible to run 58,511 tape devices simultaneously, due tothe following limits:

*
The maximum number of dump or restore operations that can runsimultaneously is 64.
*
The maximum number of tape devices that can work together on a restoreoperation is 128 (that is the maximum number of values that can beprovided for the -portoffset argument to the backup diskrestore,backup volrestore, or backup volsetrestore command).

The Backup System does not reserve UDP sockets. If another application isalready using the Tape Coordinator's socket when it tries to start, thebutc process fails and the following error message appears at the shellprompt:

   bind: Address already in use   rxi_GetUDPSocket: bind failed
 

PRIVILEGE REQUIRED

To issue any backup command that accesses the Backup Database only, theissuer must be listed in the /usr/afs/etc/UserList file on everymachine where the Backup Server is running. To issue any backup commandthat accesses volume data, the issuer must appear in the UserList fileon every Backup Server machine, every Volume Location (VL) Server machine,and every file server machine that houses affected volumes. By convention,a common UserList file is distributed to all database server and fileserver machines in the cell. See the chapter on privileged users in theIBM AFS Administration Guide for more information on this type ofprivilege.

If the -localauth flag is included, the user must instead be logged onas the local superuser root on the server machine where the backupcommand is issued. 

SEE ALSO

the BosConfig(5) manpage,the CellServDB(5) manpage,the KeyFile(5) manpage,the ThisCell(5) manpage,the UserList(5) manpage,the butc(5) manpage,the tapeconfig(5) manpage,the backup_adddump(8) manpage,the backup_addhost(8) manpage,the backup_addvolentry(8) manpage,the backup_addvolset(8) manpage,the backup_dbverify(8) manpage,the backup_deldump(8) manpage,the backup_deletedump(8) manpage,the backup_delhost(8) manpage,the backup_delvolentry(8) manpage,the backup_delvolset(8) manpage,the backup_diskrestore(8) manpage,the backup_dump(8) manpage,the backup_dumpinfo(8) manpage,the backup_help(8) manpage,the backup_interactive(8) manpage,the backup_jobs(8) manpage,the backup_kill(8) manpage,the backup_labeltape(8) manpage,the backup_listdumps(8) manpage,the backup_listhosts(8) manpage,the backup_listvolsets(8) manpage,the backup_quit(8) manpage,the backup_readlabel(8) manpage,the backup_restoredb(8) manpage,the backup_savedb(8) manpage,the backup_scantape(8) manpage,the backup_setexp(8) manpage,the backup_status(8) manpage,the backup_volinfo(8) manpage,the backup_volrestore(8) manpage,the backup_volsetrestore(8) manpage,the buserver(8) manpage,the butc(8) manpage 

COPYRIGHT

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

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


 

Index

NAME
DESCRIPTION
OPTIONS
PRIVILEGE REQUIRED
SEE ALSO
COPYRIGHT

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