BACKUP_DUMP(8) AFS Command Reference BACKUP_DUMP(8)NAMEbackup_dump - Creates a dump (dumps a volume set at a particular dump
backup dump [-volumeset <volume set name>]
[-dump <dump level name>]
[-portoffset <TC port offset>]
[-at <date/time to start dump>+]
[-file <load file>] [-localauth]
[-cell <cell name>] [-help]
backup dump [-v <volume set name>]
[-d <dump level name>]
[-p <TC port offset>]
[-at <Date/time to start dump>+] [-ap] [-n]
[-f <load file>] [-l] [-c <cell name>]
The backup dump command either dumps the volume set specified by the
-volumeset argument at the dump level specified by the -dump argument
and creates a Backup Database dump record about it, or executes the
dump instructions listed in the file named by the -file argument. The
Tape Coordinator indicated by the -portoffset argument (or on each
command in the file) executes the operation.
(If the "FILE YES" instruction appears in the
/usr/afs/backup/CFG_device_name file on the Tape Coordinator machine
associated with the specified port offset, then the Backup System dumps
data to the backup data file listed for that port offset in the Tape
Coordinator's /usr/afs/backup/tapeconfig file, rather than to 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.)
The term dumping refers to copying a collection of data to tape or a
backup data file, and the resulting collection is termed a dump. The
set of tapes that contain one or more dumps is called a dump set. The
first dump in a dump set is its initial dump, and any dumps
subsequently added to the dump set (by use of the -append argument) are
appended dumps. Creating appended dumps is optional, and appended
dumps can be of different volume sets, and at different dump levels,
than the initial dump.
A full dump, created at a full dump level in the dump hierarchy,
contains all of the data that existed at the time of the dump in the
volumes belonging to the volume set. An incremental dump, created at an
incremental dump level, contains only data that has changed since the
volume set was dumped at the incremental level's parent dump level (the
dump level immediately above the incremental level in the hierarchy),
which can be a full or incremental level. More specifically, an
incremental dump includes only the files and directories that have
modification timestamps later than the clone date of the volume
included at the parent dump level. For backup and read-only volumes,
the clone date is the time at which the volume was cloned from its
read/write source before being included in the parent dump; for
read/write volumes, it represents the time at which the volume was
locked for inclusion in the parent dump. The clone date appears in the
clone date field of the output from the backup volinfo command. As an
example, an incremental dump at the "/full/week1/thursday" level
includes only files and directories that have changed since the volume
set was dumped at the "/full/week1" level.
Initiating different types of dump operations
To initiate a dump operation that is to start as soon as the relevant
Tape Coordinator is available, provide only the -volumeset, -dump,
-portoffset, and optionally -append options. To schedule a single
backup dump command to execute in the future, also include the -at
argument to specify the start time.
To append a dump to an existing dump set, include the -append flag. The
Backup System imposes the following conditions on appended dumps:
· If writing to tape, the Tape Coordinator checks that it is the
final one in a dump set for which there are complete and valid tape
and dump records in the Backup Database. If not, it rejects the
tape and requests an acceptable one. The operator can use the
-dbadd argument to the backup scantape command to insert the
necessary records into the database.
· The most recent dump on the tape or in the backup data file must
have completed successfully.
· The dump set must begin with an initial dump that is recorded in
the Backup Database. If there are no dumps on the tape, then the
Backup System treats the dump operation as an initial dump and
imposes the relevant requirements (for example, checks the AFS tape
name if appropriate).
To schedule multiple dump operations, list the operations in the file
named by the -file argument. Optionally include the -at argument to
specify when the backup command interpreter reads the file; otherwise
it reads it immediately. Do not combine the -file argument with the
command's first three arguments or the -append or -n flags. The
commands in the file can include any of the backup dump command's
arguments, including the -at argument to schedule them to run even
later in the future.
To generate a list of the volumes included in a dump, without actually
dumping them, combine the -n flag with the options to be used on the
How the Backup System executes a dump operation
Before beginning a dump operation, the Backup System verifies that
there is a Backup Database entry for the volume set, dump level, and
port offset. If the command is correctly formed and issued in
interactive mode, it is assigned a job number and added to the jobs
list. List jobs in interactive mode by using the backup jobs command;
terminate them with the backup kill command.
After obtaining the list of volumes to dump from the Volume Location
(VL) Server, the Backup System sorts the list by site (server and
partition). It groups volumes from the same site together in the dump
to minimize the number of times the operator must change tapes during
The dependence of an incremental dump on its parent means that a valid
parent dump must already exist for the Backup System to create its
child incremental dump. If the Backup System does not find a record of
a dump created at the immediate parent dump level, it looks in the
Backup Database for a dump created at one level higher in the
hierarchy, and so on, up to the full dump level if necessary. It
creates an incremental dump at the level one below the lowest valid
parent dump set that it finds. If it fails to find even a full dump, it
dumps the volume set at the full dump level.
If the Backup System is unable to access a volume during a dump
operation, it skips the volume and dumps the remaining volumes from the
volume set. Possible reasons a volume is inaccessible include server
machine or process outages, or that the volume was moved between the
time the Volume Location (VL) Server generated the list of sites for
the volume in the volume set and the time the Backup System actually
attempts to dump the data in it. After the first dumping pass, the
Backup System attempts to dump each volume it skipped. If it still
cannot dump a volume and the "ASK NO" instruction does not appear in
the CFG_device_name file, it queries the operator as to whether it
needs to attempt to dump the volume again, omit the volume from the
dump, or halt the dump operation altogether. When prompted, the
operator can attempt to solve whatever problem prevented the Backup
System from accessing the volumes. If the "ASK NO" instruction appears
in the CFG_device_name file, the Backup System omits the volume from
Before scheduling a dump operation, the Backup System verifies that the
date specified by the -at argument is in the future, and checks the
validity of the volume set, dump level and port offset as for a regular
dump operation. It checks the validity of the parameters again just
before actually running the scheduled operation.
Before writing an initial dump to a tape that does not have a permanent
name on the label, the Backup System checks that the AFS tape name on
the label is acceptable. If desired, disable name checking by including
the "NAME_CHECK NO" instruction in the CFG_device_name file.
If AFS tape name checking is enabled, the Backup System accepts the
following three types of values for the AFS tape name. If the name on
the label does not conform, the Backup System obtains a tape with an
acceptable label by invoking the "MOUNT" instruction in the
CFG_device_name file or prompting the operator.
· A name of the form volume_set_name.dump_level_name.tape_index,
where volume_set_name matches the value of the -volumeset argument,
dump_level_name matches the last element in the pathname value of
the -dump argument, and tape_index reflects the tape's place in a
multitape dump set. As an example, the first tape in a dump set for
which the initial dump is of volume set "user" at the dump level
"/sunday2/monday" has AFS tape name "user.monday.1". If the label
records this type of AFS tape name, the Backup System retains the
AFS tape name and writes the dump to the tape.
· The string "<NULL>", which usually indicates that a backup operator
has used the backup labeltape command to write a label on the tape,
but did not include the -name argument to assign an AFS tape name.
Presumably, the operator did include the -pname argument to assign
a permanent name. If the label records a "<NULL>" value, the Backup
System constructs and records on the label the appropriate AFS tape
name, and writes the dump on the tape.
· No value at all, because the tape has never been labeled or used in
the Backup System. As when the AFS tape name is "<NULL>", the
Backup System constructs and records on the label the appropriate
AFS tape name, and writes the dump on the tape.
To determine how much data it can write to a tape, the Tape Coordinator
reads the capacity recorded on the tape's label (placed there by
including the -size argument to the backup labeltape command). If the
label's capacity field is empty, the Tape Coordinator uses the capacity
recorded for the specified port offset in the local tapeconfig file. If
the capacity field in the tapeconfig file is also empty, the Tape
Coordinator uses the maximum capacity of 2 TB.
During a dump operation, the Tape Coordinator tracks how much data it
has written and stops shortly before it reaches what it believes is the
tape's capacity. If it is in the middle of writing the data for a
volume when it reaches that point, it writes a special marker that
indicates an interrupted volume and continues writing the volume on the
next tape. It can split a volume this way during both an initial and an
appended dump, and the fact that the volume resides on multiple tapes
is automatically recorded in the Backup Database.
If the tape is actually larger than the expected capacity, then the
Tape Coordinator simply does not use the excess tape. If the tape is
smaller than the expected capacity, the Tape Coordinator can reach the
end-of-tape (EOT) unexpectedly while it is writing data. If the Tape
Coordinator is in the middle of the writing data from a volume, it
obtains a new tape and rewrites the entire contents of the interrupted
volume to it. The data from the volume that was written to the previous
tape remains there, but is never used.
The Backup System allows recycling of tapes (writing a new dump set
over an old dump set that is no longer needed), but imposes the
· All dumps in the old dump set must be expired. The Backup System
always checks expiration dates, even when name checking is
· If the tape to be recycled does not have a permanent name and name
checking is enabled, then the AFS tape name derived from the new
initial dump's volume set name and dump level name must match the
AFS tape name already recorded on the label.
· The tape cannot already have data on it that belongs to the dump
currently being performed, because that implies that the operator
or automated tape device has not removed the previous tape from the
drive, or has mistakenly reinserted it. The Tape Coordinator
generates the following message and attempts to obtain another
Can't overwrite tape containing the dump in progress
· The tape cannot contain data from a parent dump of the current
(incremental) dump, because overwriting a parent dump makes it
impossible to restore data from the current dump. The Tape
Coordinator generates the following message and attempts to obtain
Can't overwrite the parent dump I<parent_name> (I<parent_dump_ID>)
To recycle a tape before all dumps on it have expired or if the AFS
tape name is wrong, use the backup labeltape command to overwrite the
tape's label and remove all associated tape and dump records from the
The Tape Coordinator's default response to this command is to access
the first 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. It also invokes the "MOUNT" instruction or prompts for
any additional tapes needed to complete the dump operation; the issuer
must arrange to provide them.
If a dump operation is interrupted or fails for any reason, data from
all volumes written to tape before the interrupt are valid can be used
in a restore operation. The Backup Database includes an entry for the
failed dump and for each volume that was successfully dumped. See the
OpenAFS Administration Guide for information on dealing with
If dumping to tape rather than a backup data file, it is best to use
only compatible tape devices (ones that can read the same type of
tape). Using compatible devices greatly simplifies restore operations.
The -portoffset argument to the backup diskrestore and backup
volsetrestore commands accepts multiple port offset numbers, but the
Backup System uses the first listed port offset when restoring all full
dumps, the second port offset when restoring all level 1 dumps, and so
on. At the very least, use compatible tape devices to perform dumps at
each level. If compatible tape devices are not used, the backup
volrestore command must be used to restore one volume at a time.
Valid (unexpired) administrative tokens must be available to the backup
command interpreter both when it reads the file named by the -file
argument and when it runs each operation listed in the file.
Presumably, the issuer is scheduling dumps for times when no human
operator is present, and so must arrange for valid tokens to be
available on the local machine. One option is to issue all commands (or
run all scripts) on file server machines and use the -localauth flag on
the backup and vos commands. To protect against improper access to the
machine or the tokens, the machine must be physically secure (perhaps
even more protected than a Tape Coordinator machine monitored by a
human operator during operation). Also, if an unattended dump requires
multiple tapes, the operator must properly configure a tape stacker or
jukebox and the device configuration file.
When the command is issued in regular (non-interactive) mode, the
command shell prompt does not return until the dump operation
completes. To avoid having to open additional connections, issue the
command in interactive mode, especially when including the -at argument
to schedule dump operations.
OPTIONS-volumeset <volume set name>
Names the volume set to dump. The -dump argument must be provided
along with this one; do not combine them with the -file argument.
If using a temporary volume set, the vos dump command must be
issued within the interactive session in which the backup addvolset
command was issued with the -temporary flag.
-dump <dump level name>
Specifies the complete pathname of the dump level at which to dump
the volume set. The -volumeset argument must be provided along with
this one; do not combine them with the -file argument.
-portoffset <TC port offset>
Specifies the port offset number of the Tape Coordinator handling
the tapes for this operation. It must be provided unless the
default value of 0 (zero) is appropriate; do not combine it with
the -file argument.
-at <date/time to start dump>
Specifies the date and time in the future at which to run the
command, or to read the file named by the -file argument. Provide a
value in the format mm/dd/yyyy [hh:MM], where the month (mm), day
(dd), and year (yyyy) are required. Valid values for the year range
from 1970 to 2037; higher values are not valid because the latest
possible date in the standard UNIX representation is in February
2038. The Backup System automatically reduces any later date to the
The hour and minutes (hh:MM) are optional, but if provided must be
in 24-hour format (for example, the value "14:36" represents 2:36
p.m.). If omitted, the time defaults to midnight (00:00 hours).
As an example, the value 04/23/1999 20:20 schedules the command for
8:20 p.m. on 23 April 1999.
Appends the dump onto the end of a tape that already contains data
from another dump. However, if the tape is not in fact part of an
existing dump set, the Backup System creates a new dump set using
the parameters of this dump. If the tape is not the last tape in
the dump set, the Tape Coordinator prompts for insertion of the
appropriate tape. Do not combine this argument with the -file
-n Displays the names of volumes to be included in the indicated dump,
without actually performing the dump operation. Do not combine this
argument with the -file argument.
-file <load file>
Specifies the local disk or AFS pathname of a file containing
backup commands. The Backup System reads the file immediately, or
at the time specified by the -at argument if it is provided. A
partial pathname is interpreted relative to the current working
Place each backup dump command on its own line in the indicated
file, using the same syntax as for the command line, but without
the word backup at the start of the line. Each command must include
a value for the -volumeset and -dump arguments, and for the
-portoffset argument unless the default value of 0 is appropriate.
Commands in the file can also include any of the backup dump
command's optional options. In the following example file, the
first command runs as soon as the Backup System reads the file,
whereas the other commands are themselves scheduled; the specified
date and time must be later than the date and time at which the
Backup System reads the file.
dump user /sunday1/wednesday -port 1
dump sun4x_56 /sunday1/friday -port 2 -at 04/08/1999
dump sun4x_55 /sunday1/friday -port 2 -at 04/08/1999 02:00 -append
Do not combine this argument with the -volumeset, -dump,
-portoffset, -append, or -n options.
Constructs a server ticket using a key from the local
/usr/afs/etc/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
The command interpreter first generates a list of the volumes to be
included in the dump by matching the entries in the volume set against
the volumes listed in the Volume Location Database (VLDB). It prints
the list following the header:
Preparing to dump the following volumes:
The following message then indicates that the command interpreter has
passed the dump request to the appropriate Tape Coordinator for
If the issuer includes the -n flag, the output is of the following
Starting dump of volume set '<volume set>' (dump set '<dump level>')
Total number of volumes : <number dumped>
Would have dumped the following volumes:
where list_of_volumes identifies each volume by name and volume ID
If the Tape Coordinator is unable to access a volume, it prints an
error message in its window and records the error in its log and error
The following command dumps the volumes in the volume set called "user"
at the dump level "/full/sunday2/monday". The issuer places the
necessary tapes in the device with port offset 5.
% backup dump -volumeset user -dump /full/sunday2/monday -portoffset 5
Preparing to dump the following volumes:
The following command displays the list of volumes to be dumped when
the user dumps the "sys_sun" volume set at the "/full" dump level.
% backup dump -volumeset sys_sun -dump /full -n
Starting dump of volume set 'sys_sun' (dump set '/full')
Total number of volumes: 24
Would have dumped the following volumes:
The following command schedules a dump of the volumes in the volume set
"user" at the dump level "/sunday2/monday1" for 11:00 p.m. on 14 June
1999. The appropriate Tape Coordinator has port offset 0 (zero), so
that argument is omitted.
% backup dump -volumeset user -dump /sunday2/monday1 -at 06/14/1999 23:00
The issuer must be listed in the /usr/afs/etc/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".
SEE ALSObutc(5), backup(8), backup_adddump(8), backup_addvolentry(8),
backup_addvolset(8), backup_diskrestore(8), backup_labeltape(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.
OpenAFS 2013-10-09 BACKUP_DUMP(8)