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NAME | SYNOPSIS | DESCRIPTION | NOTES | EXAMPLES | FILES | SEE ALSO | DIAGNOSTICS | BUGS | COLOPHON |
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xfsdump(8) System Manager's Manual xfsdump(8)
xfsdump - XFS filesystem incremental dump utility
xfsdump -h
xfsdump [ options ] -f dest [ -f dest ... ] filesystem
xfsdump [ options ] - filesystem
xfsdump -I [ subopt=value ... ]
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.
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.
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
/var/lib/xfsdump/inventory
dump inventory database
attr(1), rmt(8), xfsrestore(8), xfsinvutil(8), xfs_quota(8),
attr_get(2).
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.
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.
This page is part of the xfsdump (XFS dump and restore) project.
Information about the project can be found at ⟨http://xfs.org/⟩.
If you have a bug report for this manual page, send it to
[email protected]. This page was obtained from the
project's upstream Git repository
⟨https://git.kernel.org/pub/scm/fs/xfs/xfsprogs-dev.git⟩ on
2024-06-14. (At that time, the date of the most recent commit
that was found in the repository was 2022-12-15.) If you
discover any rendering problems in this HTML version of the page,
or you believe there is a better or more up-to-date source for
the page, or you have corrections or improvements to the
information in this COLOPHON (which is not part of the original
manual page), send a mail to [email protected]
xfsdump(8)
Pages that refer to this page: attr(1), chacl(1), xfs(5), xfs_copy(8), xfsinvutil(8), xfsrestore(8)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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