Provided by: xfsdump_3.1.6+nmu1_amd64 
NAME
xfsdump - XFS filesystem incremental dump utility
SYNOPSIS
xfsdump -h
xfsdump [ options ] -f dest [ -f dest ... ] filesystem
xfsdump [ options ] - filesystem
xfsdump -I [ subopt=value ... ]
DESCRIPTION
xfsdump backs up files and their attributes in a filesystem. The files are dumped to storage media, a
regular file, or standard output. Options allow the operator to have all files dumped, just files that
have changed since a previous dump, or just files contained in a list of pathnames.
The xfsrestore(8) utility re-populates a filesystem with the contents of the dump.
Each invocation of xfsdump dumps just one filesystem. That invocation is termed a dump session. The
dump session splits the filesystem into one or more dump streams, one per destination. The split is done
in filesystem inode number (ino) order, at boundaries selected to equalize the size of each stream.
Furthermore, the breakpoints between streams may be in the middle of very large files (at extent
boundaries) if necessary to achieve reasonable stream size equalization. Each dump stream can span
several media objects, and a single media object can contain several dump streams. The typical media
object is a tape cartridge. The media object records the dump stream as one or more media files. A
media file is a self-contained partial dump, intended to minimize the impact of media dropouts on the
entire dump stream at the expense of increasing the time required to complete the dump. By default only
one media file is written unless a media file size is specified using the -d option. Other techniques,
such as making a second copy of the dump image, provide more protection against media failures than
multiple media files will.
xfsdump maintains an online dump inventory in /var/lib/xfsdump/inventory. The -I option displays the
inventory contents hierarchically. The levels of the hierarchy are: filesystem, dump session, stream,
and media file.
The options to xfsdump are:
-a Specifies that files for which the Data Migration Facility (DMF) has complete offline copies (dual-
state files) be treated as if they were offline (OFL). This means that the file data will not be
dumped by xfsdump, resulting in a smaller dump file. If the file is later restored the file data is
still accessible through DMF. If both '-a option' and '-z option' are specified, the '-a option'
takes precedence (see '-z option' below).
-b blocksize
Specifies the blocksize, in bytes, to be used for the dump. The same blocksize must be specified to
restore the tape. If the -m option is not used, then -b does not need to be specified. Instead, a
default blocksize of 1Mb will be used.
-c progname
Use the specified program to alert the operator when a media change is required. The alert program
is typically a script to send a mail or flash a window to draw the operator's attention.
-d filesize
Specifies the size, in megabytes, of dump media files. If not specified, xfsdump will dump data to
tape using a single media file per media object. The specified media file size may need to be
adjusted if, for example, xfsdump cannot fit a media file onto a single tape.
-e Allow files to be excluded from the dump. This will cause xfsdump to skip files which have the "no
dump" file attribute set. See the "Excluding individual files" section below for details on setting
this file attribute.
-f dest [ -f dest ... ]
Specifies a dump destination. A dump destination can be the pathname of a device (such as a tape
drive), a regular file or a remote tape drive (see rmt(8)). This option must be omitted if the
standard output option (a lone - preceding the source filesystem specification) is specified.
-l level
Specifies a dump level of 0 to 9. The dump level determines the base dump to which this dump is
relative. The base dump is the most recent dump at a lesser level. A level 0 dump is absolute -
all files are dumped. A dump level where 1 <= level <= 9 is referred to as an incremental dump.
Only files that have been changed since the base dump are dumped. Subtree dumps (see the -s option
below) cannot be used as the base for incremental dumps.
-m Use the minimal tape protocol for non-scsi tape destinations or remote tape destinations which are
not scsi Linux tape drives nor IRIX tape drives. This option cannot be used without specifying a
blocksize to be used (see -b option above).
-o Overwrite the tape. With this option, xfsdump does not read the tape first to check the contents.
This option may be used if xfsdump is unable to determine the block size of a tape .
-p interval
Causes progress reports to be printed at the specified interval. interval is given in seconds. The
progress report indicates how many files have been dumped, the total number of files to dump, the
percentage of data dumped, and the elapsed time.
-q Destination tape drive is a QIC tape. QIC tapes only use a 512 byte blocksize, for which xfsdump
must make special allowances.
-s pathname [ -s pathname ... ]
Restricts the dump to files contained in the specified pathnames (subtrees). A pathname must be
relative to the mount point of the filesystem. For example, if a filesystem is mounted at /d2, the
pathname argument for the directory /d2/users is ``users''. A pathname can be a file or a
directory; if it is a directory, the entire hierarchy of files and subdirectories rooted at that
directory is dumped. Subtree dumps cannot be used as the base for incremental dumps (see the -l
option above).
-t file
Sets the dump time to the modification time of file rather than using the current time. xfsdump
uses the dump time to determine what files need to be backed up during an incremental dump. This
option should be used when dumping snapshots so that the dump time matches the time the snapshot was
taken. Otherwise files modified after a snapshot is taken may be skipped in the next incremental
dump.
-v verbosity
-v subsys=verbosity[,subsys=verbosity,...]
Specifies the level of detail used for messages displayed during the course of the dump. The
verbosity argument can be passed as either a string or an integer. If passed as a string the
following values may be used: silent, verbose, trace, debug, or nitty. If passed as an integer,
values from 0-5 may be used. The values 0-4 correspond to the strings already listed. The value 5
can be used to produce even more verbose debug output.
The first form of this option activates message logging across all dump subsystems. The second form
allows the message logging level to be controlled on a per-subsystem basis. The two forms can be
combined (see the example below). The argument subsys can take one of the following values: general,
proc, drive, media, inventory, inomap and excluded_files.
For example, to dump the root filesystem with tracing activated for all subsystems:
# xfsdump -v trace -f /dev/tape /
To enable debug-level tracing for drive and media operations:
# xfsdump -v drive=debug,media=debug -f /dev/tape /
To enable tracing for all subsystems, and debug level tracing for drive operations only:
# xfsdump -v trace,drive=debug -f /dev/tape /
To list files that will be excluded from the dump:
# xfsdump -e -v excluded_files=debug -f /dev/tape /
-z size
Specifies the maximum size, in kilobytes, of files to be included in the dump. Files over this
size, will be excluded from the dump, except for DMF dual-state files when '-a option' is specified
(see '-a option' above). When specified, '-a option' takes precedence over '-z option'. The size is
an estimate based on the number of disk blocks actually used by the file, and so does not include
holes. In other words, size refers to the amount of space the file would take in the resulting
dump. On an interactive restore, the skipped file is visible with xfsrestore's 'ls' and while you
can use the 'add' and 'extract' commands, nothing will be restored.
-A Do not dump extended file attributes. When dumping a filesystem managed within a DMF environment
this option should not be used. DMF stores file migration status within extended attributes
associated with each file. If these attributes are not preserved when the filesystem is restored,
files that had been in migrated state will not be recallable by DMF. Note that dumps containing
extended file attributes cannot be restored with older versions of xfsrestore(8).
-B session_id
Specifies the ID of the dump session upon which this dump session is to be based. If this option is
specified, the -l (level) and -R (resume) options are not allowed. Instead, xfsdump determines if
the current dump session should be incremental and/or resumed, by looking at the base session's
level and interrupted attributes. If the base session was interrupted, the current dump session is
a resumption of that base at the same level. Otherwise, the current dump session is an incremental
dump with a level one greater than that of the base session. This option allows incremental and
resumed dumps to be based on any previous dump, rather than just the most recent.
-D Controls which directories are backed up during an incremental dump. By default unchanged
directories are dumped if files or directories beneath them have changed. This results in a self-
contained dump -- if a base dump is lost, or you know the file(s) you wish to restore is in an
incremental dump, you can restore just that dump without loading the base dump(s) first. However,
this method requires a potentially expensive traversal through the filesystem.
When -D is specified, unchanged directories are not dumped. This results in a faster dump, but
files will end up in the xfsrestore(8) orphanage directory unless the base dump(s) is loaded first.
-E Pre-erase media. If this option is specified, media is erased prior to use. The operator is
prompted for confirmation, unless the -F option is also specified.
-F Don't prompt the operator. When xfsdump encounters a media object containing non-xfsdump data,
xfsdump normally asks the operator for permission to overwrite. With this option the overwrite is
performed, no questions asked. When xfsdump encounters end-of-media during a dump, xfsdump normally
asks the operator if another media object will be provided. With this option the dump is instead
interrupted.
-I Displays the xfsdump inventory (no dump is performed). xfsdump records each dump session in an
online inventory in /var/lib/xfsdump/inventory. xfsdump uses this inventory to determine the base
for incremental dumps. It is also useful for manually identifying a dump session to be restored.
Suboptions to filter the inventory display are described later.
-J Inhibits the normal update of the inventory. This is useful when the media being dumped to will be
discarded or overwritten.
-K Generate a format 2 dump instead of the current format. This is useful if the dump will be restored
on a system with an older xfsrestore which does not understand the current dump format. Use of this
option is otherwise not recommended.
-L session_label
Specifies a label for the dump session. It can be any arbitrary string up to 255 characters long.
-M label [ -M label ... ]
Specifies a label for the first media object (for example, tape cartridge) written on the
corresponding destination during the session. It can be any arbitrary string up to 255 characters
long. Multiple media object labels can be specified, one for each destination.
-O options_file
Insert the options contained in options_file into the beginning of the command line. The options
are specified just as they would appear if typed into the command line. In addition, newline
characters (\n) can be used as whitespace. The options are placed before all options actually given
on the command line, just after the command name. Only one -O option can be used. Recursive use is
ignored. The source filesystem cannot be specified in options_file.
-R Resumes a previously interrupted dump session. If the most recent dump at this dump's level (-l
option) was interrupted, this dump contains only files not in the interrupted dump and consistent
with the incremental level. However, files contained in the interrupted dump that have been
subsequently modified are re-dumped.
-T Inhibits interactive dialogue timeouts. When the -F option is not specified, xfsdump prompts the
operator for labels and media changes. Each dialogue normally times out if no response is supplied.
This option prevents the timeout.
-Y length
Specify I/O buffer ring length. xfsdump uses a ring of output buffers to achieve maximum throughput
when dumping to tape drives. The default ring length is 3. However, this is not currently enabled
on Linux yet, making this option benign.
- A lone - causes the dump stream to be sent to the standard output, where it can be piped to another
utility such as xfsrestore(8) or redirected to a file. This option cannot be used with the -f
option. The - must follow all other options and precede the filesystem specification.
The filesystem, filesystem, can be specified either as a mount point or as a special device file (for
example, /dev/dsk/dks0d1s0). The filesystem must be mounted to be dumped.
NOTES
Dump Interruption
A dump can be interrupted at any time and later resumed. To interrupt, type control-C (or the current
terminal interrupt character). The operator is prompted to select one of several operations, including
dump interruption. After the operator selects dump interruption, the dump continues until a convenient
break point is encountered (typically the end of the current file). Very large files are broken into
smaller subfiles, so the wait for the end of the current file is brief.
Dump Resumption
A previously interrupted dump can be resumed by specifying the -R option. If the most recent dump at the
specified level was interrupted, the new dump does not include files already dumped, unless they have
changed since the interrupted dump.
Media Management
A single media object can contain many dump streams. Conversely, a single dump stream can span multiple
media objects. If a dump stream is sent to a media object already containing one or more dumps, xfsdump
appends the new dump stream after the last dump stream. Media files are never overwritten. If end-of-
media is encountered during the course of a dump, the operator is prompted to insert a new media object
into the drive. The dump stream continuation is appended after the last media file on the new media
object.
Inventory
Each dump session updates an inventory database in /var/lib/xfsdump/inventory. xfsdump uses the
inventory to determine the base of incremental and resumed dumps.
This database can be displayed by invoking xfsdump with the -I option. The display uses tabbed
indentation to present the inventory hierarchically. The first level is filesystem. The second level is
session. The third level is media stream (currently only one stream is supported). The fourth level
lists the media files sequentially composing the stream.
The following suboptions are available to filter the display.
-I depth=n
(where n is 1, 2, or 3) limits the hierarchical depth of the display. When n is 1, only the
filesystem information from the inventory is displayed. When n is 2, only filesystem and session
information are displayed. When n is 3, only filesystem, session and stream information are
displayed.
-I level=n
(where n is the dump level) limits the display to dumps of that particular dump level.
The display may be restricted to media files contained in a specific media object.
-I mobjid=value
(where value is a media ID) specifies the media object by its media ID.
-I mobjlabel=value
(where value is a media label) specifies the media object by its media label.
Similarly, the display can be restricted to a specific filesystem.
-I mnt=mount_point
(that is, [hostname:]pathname), identifies the filesystem by mountpoint. Specifying the hostname is
optional, but may be useful in a clustered environment where more than one host can be responsible
for dumping a filesystem.
-I fsid=filesystem_id
identifies the filesystem by filesystem ID.
-I dev=device_pathname
(that is, [hostname:]device_pathname) identifies the filesystem by device. As with the mnt filter,
specifying the hostname is optional.
More than one of these suboptions, separated by commas, may be specified at the same time to limit the
display of the inventory to those dumps of interest. However, at most four suboptions can be specified
at once: one to constrain the display hierarchy depth, one to constrain the dump level, one to constrain
the media object, and one to constrain the filesystem.
For example, -I depth=1,mobjlabel="tape 1",mnt=host1:/test_mnt would display only the filesystem
information (depth=1) for those filesystems that were mounted on host1:/test_mnt at the time of the dump,
and only those filesystems dumped to the media object labeled "tape 1".
Dump records may be removed (pruned) from the inventory using the xfsinvutil program.
An additional media file is placed at the end of each dump stream. This media file contains the
inventory information for the current dump session. Its contents may be merged back into the online
inventory database at a later time using xfsrestore(1M).
The inventory files stored in /var/lib/xfsdump are not included in the dump, even if that directory is
contained within the filesystem being dumped. Including the inventory in the dump may lead to loss or
corruption of data, should an older version be restored overwriting the current version. To backup the
xfsdump inventory, the contents of /var/lib/xfsdump should be copied to another location which may then
be safely dumped. Upon restoration, those files may be copied back into /var/lib/xfsdump, overwriting
whatever files may be there, or xfsinvutil(1M) may be used to selectively merge parts of the restored
inventory back into the current inventory. Prior to version 1.1.8, xfsdump would include the
/var/lib/xfsdump directory in the dump. Care should be taken not to overwrite the /var/lib/xfsdump
directory when restoring an old dump, by either restoring the filesystem to another location or by
copying the current contents of /var/lib/xfsdump to a safe place prior to running xfsrestore(1M).
Labels
The operator can specify a label to identify the dump session and a label to identify a media object.
The session label is placed in every media file produced in the course of the dump, and is recorded in
the inventory.
The media label is used to identify media objects, and is independent of the session label. Each media
file on the media object contains a copy of the media label. An error is returned if the operator
specifies a media label that does not match the media label on a media object containing valid media
files. Media labels are recorded in the inventory.
UUIDs
UUIDs (Universally Unique Identifiers) are used in three places: to identify the filesystem being dumped
(using the filesystem UUID, see xfs(5) for more details), to identify the dump session, and to identify
each media object. The inventory display (-I) includes all of these.
Dump Level Usage
The dump level mechanism provides a structured form of incremental dumps. A dump of level level includes
only files that have changed since the most recent dump at a level less than level. For example, the
operator can establish a dump schedule that involves a full dump every Friday and a daily incremental
dump containing only files that have changed since the previous dump. In this case Friday's dump would
be at level 0, Saturday's at level 1, Sunday's at level 2, and so on, up to the Thursday dump at level 6.
The above schedule results in a very tedious restore procedure to fully reconstruct the Thursday version
of the filesystem; xfsrestore would need to be fed all 7 dumps in sequence. A compromise schedule is to
use level 1 on Saturday, Monday, and Wednesday, and level 2 on Sunday, Tuesday, and Thursday. The Monday
and Wednesday dumps would take longer, but the worst case restore requires the accumulation of just three
dumps, one each at level 0, level 1, and level 2.
Quotas
If the filesystem being dumped contains user quotas, xfsdump will use xfs_quota(8) to store the quotas in
a file called xfsdump_quotas in the root of the filesystem to be dumped. This file will then be included
in the dump. Upon restoration, xfs_quota (8) can be used to reactivate the quotas for the filesystem.
Note, however, that the xfsdump_quotas file will probably require modification to change the filesystem
or UIDs if the filesystem has been restored to a different partition or system. Group and project quotas
will be handled in a similar fashion and saved in files called xfsdump_quotas_group and
xfsdump_quotas_proj , respectively.
Excluding individual files
It may be desirable to exclude particular files or directories from the dump. The -s option can be used
to limit the dump to a specified directory, and the -z option can be used to exclude files over a
particular size. Additionally, when xfsdump is run with the -e option, files that are tagged with the
"no dump" file attribute will not be included in the dump. The chattr(1) command can be used to set this
attribute on individual files or entire subtrees.
To tag an individual file for exclusion from the dump:
$ chattr +d file
To tag all files in a subtree for exclusion from the dump:
$ chattr -R +d directory
Note that any new files or directories created in a directory which has the "no dump" attribute set will
automatically inherit this attribute. Also note that xfsdump does not check directories for the "no
dump" attribute.
Care should be taken to note which files have been tagged. Under normal operation, xfsdump will only
report the number of files it will skip. The -v excluded_files=debug option, however, will cause xfsdump
to list the inode numbers of the individual files affected.
EXAMPLES
To perform a level 0, single stream dump of the root filesystem to a locally mounted tape drive,
prompting for session and media labels when required:
# xfsdump -f /dev/tape /
To specify session and media labels explicitly:
# xfsdump -L session_1 -M tape_0 -f /dev/tape /
To perform a dump to a remote tape using the minimal rmt protocol and a set blocksize of 64k:
# xfsdump -m -b 65536 -f otherhost:/dev/tape /
To perform a level 0, multi-stream dump to two locally mounted tape drives:
# xfsdump -L session_2 -f /dev/rmt/tps4d6v -M tape_1 \
-f /dev/rmt/tps5d6v -M tape_2 /
To perform a level 1 dump relative to the last level 0 dump recorded in the inventory:
# xfsdump -l 1 -f /dev/tape /
To copy the contents of a filesystem to another directory (see xfsrestore(8)):
# xfsdump -J - / | xfsrestore -J - /new
FILES
/var/lib/xfsdump/inventory
dump inventory database
SEE ALSO
attr(1), rmt(8), xfsrestore(8), xfsinvutil(8), xfs_quota(8), attr_get(2).
DIAGNOSTICS
The exit code is 0 on normal completion, non-zero if an error occurs or the dump is terminated by the
operator.
For all verbosity levels greater than 0 (silent) the final line of the output shows the exit status of
the dump. It is of the form:
xfsdump: Dump Status: code
Where code takes one of the following values: SUCCESS (normal completion), INTERRUPT (interrupted), QUIT
(media no longer usable), INCOMPLETE (dump incomplete), FAULT (software error), and ERROR (resource
error). Every attempt will be made to keep both the syntax and the semantics of this log message
unchanged in future versions of xfsdump. However, it may be necessary to refine or expand the set of
exit codes, or their interpretation at some point in the future.
The message ``xfsdump: WARNING: unable to open directory: ino N: Invalid argument'' can occur with
filesystems which are actively being modified while xfsdump is running. This can happen to either
directory or regular file inodes - affected files will not end up in the dump, files below affected
directories will be placed in the orphanage directory by xfsrestore.
BUGS
xfsdump does not dump unmounted filesystems.
The dump frequency field of /etc/fstab is not supported.
xfsdump uses the alert program only when a media change is required.
xfsdump requires root privilege (except for inventory display).
xfsdump can only dump XFS filesystems.
The media format used by xfsdump can only be understood by xfsrestore.
xfsdump does not know how to manage CD-ROM or other removable disk drives.
xfsdump can become confused when doing incremental or resumed dumps if on the same machine you dump two
XFS filesystems and both filesystems have the same filesystem identifier (UUID). Since xfsdump uses the
filesystem identifier to identify filesystems, xfsdump maintains one combined set of dump inventories for
both filesystems instead of two sets of dump inventories. This scenario can happen only if dd or some
other block-by-block copy program was used to make a copy of an XFS filesystem. See xfs_copy(8) and
xfs(5) for more details.
xfsdump(8)