NAME
xfsrestore - XFS filesystem incremental restore utility
SYNOPSIS
xfsrestore -h
xfsrestore [ options ] -f source [ -f source ... ] dest
xfsrestore [ options ] - dest
xfsrestore -I [ subopt=value ... ]
DESCRIPTION
xfsrestore restores filesystems from dumps produced by xfsdump(8). Two
modes of operation are available: simple and cumulative.
The default is simple mode. xfsrestore populates the specified
destination directory, dest, with the files contained in the dump
media.
The -r option specifies the cumulative mode. Successive invocations of
xfsrestore are used to apply a chronologically ordered sequence of
delta dumps to a base (level 0) dump. The contents of the filesystem
at the time each dump was produced is reproduced. This can involve
adding, deleting, renaming, linking, and unlinking files and
directories.
A delta dump is defined as either an incremental dump (xfsdump -l
option with level > 0) or a resumed dump (xfsdump -R option). The
deltas must be applied in the order they were produced. Each delta
applied must have been produced with the previously applied delta as
its base.
The options to xfsrestore are:
-a housekeeping
Each invocation of xfsrestore creates a directory called
xfsrestorehousekeepingdir. This directory is normally created
directly under the dest directory. The -a option allows the
operator to specify an alternate directory, housekeeping, in which
xfsrestore creates the xfsrestorehousekeeping directory. When
performing a cumulative (-r option) restore, each successive
invocation of xfsrestore must specify the same alternate
directory.
-b blocksize
Specifies the blocksize, in bytes, to be used for the restore.
For other drives such as DAT or 8 mm , the same blocksize used for
the xfsdump operation must be specified to restore the tape. The
default block size is 1Mb.
-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.
-e Prevents xfsrestore from overwriting existing files in the dest
directory.
-f source [ -f source ... ]
Specifies a source of the dump to be restored. This 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 input option (a lone - preceding the dest
specification) is specified.
-i Selects interactive operation. Once the on-media directory
hierarchy has been read, an interactive dialogue is begun. The
operator uses a small set of commands to peruse the directory
hierarchy, selecting files and subtrees for extraction. The
available commands are given below. Initially nothing is
selected, except for those subtrees specified with -s command line
options.
ls [arg] List the entries in the current directory or the
specified directory, or the specified non-directory
file entry. Both the entry’s original inode number
and name are displayed. Entries that are
directories are appended with a ‘/’. Entries that
have been selected for extraction are prepended
with a ‘*’.
cd [arg] Change the current working directory to the
specified argument, or to the filesystem root
directory if no argument is specified.
pwd Print the pathname of the current directory,
relative to the filesystem root.
add [arg] The current directory or specified file or
directory within the current directory is selected
for extraction. If a directory is specified, then
it and all its descendents are selected. Entries
that are selected for extraction are prepended with
a ‘*’ when they are listed by ls.
delete [arg] The current directory or specified file or
directory within the current directory is
deselected for extraction. If a directory is
specified, then it and all its descendents are
deselected. The most expedient way to extract most
of the files from a directory is to select the
directory and then deselect those files that are
not needed.
extract Ends the interactive dialogue, and causes all
selected subtrees to be restored.
quit xfsrestore ends the interactive dialogue and
immediately exits, even if there are files or
subtrees selected for extraction.
help List a summary of the available commands.
-m Use the minimal tape protocol. This option cannot be used without
specifying a blocksize to be used (see -b option above).
-n file
Allows xfsrestore to restore only files newer than file. The
modification time of file (i.e., as displayed with the ls -l
command) is compared to the inode modification time of each file
on the source media (i.e., as displayed with the ls -lc command).
A file is restored from media only if its inode modification time
is greater than or equal to the modification time of file.
-o Restore file and directory owner/group even if not root. When run
with an effective user id of root, xfsrestore restores owner and
group of each file and directory. When run with any other
effective user id it does not, unless this option is specified.
-p interval
Causes progress reports to be printed at intervals of interval
seconds. The interval value is approximate, xfsrestore will delay
progress reports to avoid undue processing overhead.
-q Source tape drive is a QIC tape. QIC tapes only use a 512 byte
blocksize, for which xfsrestore must make special allowances.
-r Selects the cumulative mode of operation.
-s subtree
Specifies a subtree to restore. Any number of -s options are
allowed. The restore is constrained to the union of all subtrees
specified. Each subtree is specified as a pathname relative to
the restore dest. If a directory is specified, the directory and
all files beneath that directory are restored.
-t Displays the contents of the dump, but does not create or modify
any files or directories. It may be desirable to set the
verbosity level to silent when using this option.
-v verbosity
-v subsys=verbosity[,subsys=verbosity,...]
Specifies the level of detail used for messages displayed during
the course of the restore. 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
restore 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, and tree.
For example, to restore the root filesystem with tracing activated
for all subsystems:
# xfsrestore -v trace -f /dev/tape /
To enable debug-level tracing for drive and media operations:
# xfsrestore -v drive=debug,media=debug -f /dev/tape /
To enable tracing for all subsystems, and debug level tracing for
drive operations only:
# xfsrestore -v trace,drive=debug -f /dev/tape /
-A Do not restore extended file attributes. When restoring 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 dumping of
extended file attributes is also optional.
-B Change the ownership and permissions of the destination directory
to match those of the root directory of the dump.
-D Restore DMAPI (Data Management Application Programming Interface)
event settings. If the restored filesystem will be managed within
the same DMF environment as the original dump it is essential that
the -D option be used. Otherwise it is not usually desirable to
restore these settings.
-E Prevents xfsrestore from overwriting newer versions of files. The
inode modification time of the on-media file is compared to the
inode modification time of corresponding file in the dest
directory. The file is restored only if the on-media version is
newer than the version in the dest directory. The inode
modification time of a file can be displayed with the ls -lc
command.
-F Inhibit interactive operator prompts. This option inhibits
xfsrestore from prompting the operator for verification of the
selected dump as the restore target and from prompting for any
media change.
-I Causes the xfsdump inventory to be displayed (no restore is
performed). Each time xfsdump is used, an online inventory in
/var/lib/xfsdump/inventory is updated. This is used to determine
the base for incremental dumps. It is also useful for manually
identifying a dump session to be restored (see the -L and -S
options). Suboptions to filter the inventory display are
described later.
-J Inhibits inventory update when on-media session inventory
encountered during restore. xfsrestore opportunistically updates
the online inventory when it encounters an on-media session
inventory, but only if run with an effective user id of root and
only if this option is not given.
-L session_label
Specifies the label of the dump session to be restored. The
source media is searched for this label. It is any arbitrary
string up to 255 characters long. The label of the desired dump
session can be copied from the inventory display produced by the
-I option.
-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 destination directory cannot be specified in
options_file.
-Q Force completion of an interrupted restore session. This option
is required to work around one specific pathological scenario.
When restoring a dump session which was interrupted due to an EOM
condition and no online session inventory is available, xfsrestore
cannot know when the restore of that dump session is complete.
The operator is forced to interrupt the restore session. In that
case, if the operator tries to subsequently apply a resumed dump
(using the -r option), xfsrestore refuses to do so. The operator
must tell xfsrestore to consider the base restore complete by
using this option when applying the resumed dump.
-R Resume a previously interrupted restore. xfsrestore can be
interrupted at any time by pressing the terminal interrupt
character (see stty(1)). Use this option to resume the restore.
The -a and destination options must be the same.
-S session_id
Specifies the session UUID of the dump session to be restored.
The source media is searched for this UUID. The UUID of the
desired dump session can be copied from the inventory display
produced by the -I option.
-T Inhibits interactive dialogue timeouts. xfsrestore prompts the
operator for media changes. This dialogue normally times out if
no response is supplied. This option prevents the timeout.
-X subtree
Specifies a subtree to exclude. This is the converse of the -s
option. Any number of -X options are allowed. Each subtree is
specified as a pathname relative to the restore dest. If a
directory is specified, the directory and all files beneath that
directory are excluded.
-Y io_ring_length
Specify I/O buffer ring length. xfsrestore uses a ring of input
buffers to achieve maximum throughput when restoring from tape
drives. The default ring length is 3. However, this is only
supported when running multi-threaded which has not been done for
Linux yet - making this option benign.
- A lone - causes the standard input to be read as the source of the
dump to be restored. Standard input can be a pipe from another
utility (such as xfsdump(8)) or a redirected file. This option
cannot be used with the -f option. The - must follow all other
options, and precede the dest specification.
The dumped filesystem is restored into the dest directory. There is no
default; the dest must be specified.
NOTES
Cumulative Restoration
A base (level 0) dump and an ordered set of delta dumps can be
sequentially restored, each on top of the previous, to reproduce the
contents of the original filesystem at the time the last delta was
produced. The operator invokes xfsrestore once for each dump. The -r
option must be specified. The dest directory must be the same for all
invocations. Each invocation leaves a directory named
xfsrestorehousekeeping in the dest directory (however, see the -a
option above). This directory contains the state information that must
be communicated between invocations. The operator must remove this
directory after the last delta has been applied.
xfsrestore also generates a directory named orphanage in the dest
directory. xfsrestore removes this directory after completing a simple
restore. However, if orphanage is not empty, it is not removed. This
can happen if files present on the dump media are not referenced by any
of the restored directories. The orphanage has an entry for each such
file. The entry name is the file’s original inode number, a ".", and
the file’s generation count modulo 4096 (only the lower 12 bits of the
generation count are used).
xfsrestore does not remove the orphanage after cumulative restores.
Like the xfsrestorehousekeeping directory, the operator must remove it
after applying all delta dumps.
Media Management
A dump consists of one or more media files contained on one or more
media objects. A media file contains all or a portion of the
filesystem dump. Large filesystems are broken up into multiple media
files to minimize the impact of media dropouts, and to accommodate
media object boundaries (end-of-media).
A media object is any storage medium: a tape cartridge, a remote tape
device (see rmt(8)), a regular file, or the standard input (currently
other removable media drives are not supported). Tape cartridges can
contain multiple media files, which are typically separated by (in tape
parlance) file marks. If a dump spans multiple media objects, the
restore must begin with the media object containing the first media
file dumped. The operator is prompted when the next media object is
needed.
Media objects can contain more than one dump. The operator can select
the desired dump by specifying the dump label (-L option), or by
specifying the dump UUID (-S option). If neither is specified,
xfsrestore scans the entire media object, prompting the operator as
each dump session is encountered.
The inventory display (-I option) is useful for identifying the media
objects required. It is also useful for identifying a dump session.
The session UUID can be copied from the inventory display to the -S
option argument to unambiguously identify a dump session to be
restored.
Dumps placed in regular files or the standard output do not span
multiple media objects, nor do they contain multiple dumps.
Inventory
Each dump session updates an inventory database in
/var/lib/xfsdump/inventory. This database can be displayed by invoking
xfsrestore 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. If the online inventory files in /var/lib/xfsdump/inventory
are missing information for the current dump session, then the
inventory information in the media file is automatically added to the
files in /var/lib/xfsdump/inventory. If you wish to incorporate the
inventory information from the media file without restoring any data,
you may do so using the -t option:
# xfsrestore -t -f /dev/tape
This is useful to rebuild the inventory database if it is ever lost or
corrupted. The only caveat is that xfsrestore needs to read through
the entire dump in order to reach the inventory media file. This could
become time consuming for dump sessions with large media files.
Media Errors
xfsdump is tolerant of media errors, but cannot do error correction.
If a media error occurs in the body of a media file, the filesystem
file represented at that point is lost. The bad portion of the media
is skipped, and the restoration resumes at the next filesystem file
after the bad portion of the media.
If a media error occurs in the beginning of the media file, the entire
media file is lost. For this reason, large dumps are broken into a
number of reasonably sized media files. The restore resumes with the
next media file.
Quotas
When xfsdump dumps a filesystem with user quotas, it creates a file in
the root of the dump called xfsdump_quotas. xfsrestore can restore
this file like any other file included in the dump. This file can be
processed by the restore command of xfs_quota(8) to reactivate the
quotas. However, the xfsdump_quotas file contains information which
may first require modification; specifically the filesystem name and
the user ids. If you are restoring the quotas for the same users on
the same filesystem from which the dump was taken, then no modification
will be necessary. However, if you are restoring the dump to a
different filesystem, you will need to:
- ensure the new filesystem is mounted with the quota option
- modify the xfsdump_quotas file to contain the new filesystem name
- ensure the uids in the xfsdump_quotas file are correct
Once the quota information has been verified, the restore command of
xfs_quota (8) can be used to apply the quota limits to the filesystem.
Group and project quotas are handled in a similar fashion and will be
restored in files called xfsdump_quotas_group and xfsdump_quotas_proj,
respectively.
EXAMPLES
To restore the root filesystem from a locally mounted tape:
# xfsrestore -f /dev/tape /
To restore from a remote tape, specifying the dump session id:
# xfsrestore -L session_1 -f otherhost:/dev/tape /new
To restore the contents a of a dump to another subdirectory:
# xfsrestore -f /dev/tape /newdir
To copy the contents of a filesystem to another directory (see
xfsdump(8)):
# xfsdump -J - / | xfsrestore -J - /new
FILES
/var/lib/xfsdump/inventory
dump inventory database
SEE ALSO
rmt(8), xfsdump(8), xfsinvutil(8), xfs_quota(8), attr_set(2).
DIAGNOSTICS
The exit code is 0 on normal completion, and non-zero if an error
occurred or the restore was terminated by the operator.
For all verbosity levels greater than 0 (silent) the final line of the
output shows the exit status of the restore. It is of the form:
xfsdump: Restore Status: code
Where code takes one of the following values: SUCCESS (normal
completion), INTERRUPT (interrupted), QUIT (media no longer usable),
INCOMPLETE (restore 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
xfsrestore. However, it may be necessary to refine or expand the set
of exit codes, or their interpretation at some point in the future.
BUGS
Pathnames of restored non-directory files (relative to the dest
directory) must be 1023 characters (MAXPATHLEN) or less. Longer
pathnames are discarded and a warning message displayed.
There is no verify option to xfsrestore. This would allow the operator
to compare a filesystem dump to an existing filesystem, without
actually doing a restore.
The interactive commands (-i option) do not understand regular
expressions.
When the minimal rmt option is specified, xfsrestore applies it to all
remote tape sources. The same blocksize (specified by the -b option) is
used for all these remote drives.
xfsrestore uses the alert program only when a media change is required.
Cumulative mode (-r option) requires that the operator invoke
xfsrestore for the base and for each delta to be applied in sequence to
the base. It would be better to allow the operator to identify the
last delta in the sequence of interest, and let xfsrestore work
backwards from that delta to identify and apply the preceding deltas
and base dump, all in one invocation.
xfsrestore(8)