Provided by: xfsprogs_6.8.0-2.2ubuntu1_amd64 
NAME
xfs_metadump - copy XFS filesystem metadata to a file
SYNOPSIS
xfs_metadump [ -aefFgow ] [ -m max_extents ] [ -l logdev ] [ -v version ] source target
xfs_metadump -V
DESCRIPTION
xfs_metadump is a debugging tool that copies the metadata from an XFS filesystem to a
file. The source argument must be the pathname of the device or file containing the XFS
filesystem and the target argument specifies the destination file name. If target is -,
then the output is sent to stdout. This allows the output to be redirected to another
program such as a compression application.
xfs_metadump may only be used to copy unmounted filesystems, or read-only mounted
filesystems.
xfs_metadump does not alter the source filesystem in any way. The target image is a
contiguous (non-sparse) file containing all the filesystem's metadata and indexes to where
the blocks were copied from.
By default, xfs_metadump obfuscates most file (regular file, directory and symbolic link)
names and extended attribute names to allow the dumps to be sent without revealing
confidential information. Extended attribute values are zeroed and no data is copied. The
only exceptions are file or attribute names that are 4 or less characters in length. Also
file names that span extents (this can only occur with the mkfs.xfs(8) options where -n
size > -b size) are not obfuscated. Names between 5 and 8 characters in length inclusively
are partially obfuscated.
xfs_metadump cannot obfuscate metadata in the filesystem log. Log recovery of an
obfuscated metadump image may expose clear-text metadata and/or cause filesystem
corruption in the restored image. It is recommended that the source filesystem first be
mounted and unmounted, if possible, to ensure that the log is clean. A subsequent
invocation of xfs_metadump will capture a clean log and obfuscate all metadata correctly.
If a metadump must be produced from a filesystem with a dirty log, it is recommended that
obfuscation be turned off with -o option, if metadata such as filenames is not considered
sensitive. If obfuscation is required on a metadump with a dirty log, please inform the
recipient of the metadump image about this situation.
The contents of an external log device can be dumped only when using the v2 format.
Metadump in v2 format can be generated by passing the "-v 2" option. Metadump in v2
format is generated by default if the filesystem has an external log and the metadump
version to use is not explicitly mentioned.
xfs_metadump should not be used for any purposes other than for debugging and reporting
filesystem problems. The most common usage scenario for this tool is when xfs_repair(8)
fails to repair a filesystem and a metadump image can be sent for analysis.
The file generated by xfs_metadump can be restored to filesystem image (minus the data)
using the xfs_mdrestore(8) tool.
OPTIONS
-a Copies entire metadata blocks. Normally, xfs_metadump will zero any stale bytes
interspersed with in-use metadata. Use this option to copy full metadata blocks,
to provide more debugging information for a corrupted filesystem. Note that the
extra data will be unobfuscated.
-e Stops the dump on a read error. Normally, it will ignore read errors and copy all
the metadata that is accessible.
-f Specifies that the filesystem image to be processed is stored in a regular file
(see the mkfs.xfs -d file option). This can also happen if an image copy of a
filesystem has been made into an ordinary file with xfs_copy(8).
-F Specifies that we want to continue even if the superblock magic is not correct. If
the source is truly not an XFS filesystem, the resulting image will be useless, and
xfs_metadump may crash.
-g Shows dump progress. This is sent to stdout if the target is a file or to stderr if
the target is stdout.
-l logdev
For filesystems which use an external log, this specifies the device where the
external log resides. If the v2 metadump format is selected, the contents of the
external log will be copied to the metadump. The v2 metadump format will be
selected automatically if this option is specified.
-m Set the maximum size of an allowed metadata extent. Extremely large metadata
extents are likely to be corrupt, and will be skipped if they exceed this value.
The default size is 2097151 blocks.
-o Disables obfuscation of file names and extended attributes.
-v The format of the metadump file to be produced. Valid values are 1 and 2. The
default metadump format is 1.
-w Prints warnings of inconsistent metadata encountered to stderr. Bad metadata is
still copied.
-V Prints the version number and exits.
DIAGNOSTICS
xfs_metadump returns an exit code of 0 if all readable metadata is successfully copied or
1 if a write error occurs or a read error occurs and the -e option used.
NOTES
As xfs_metadump copies metadata only, it does not matter if the source filesystem has a
realtime section or not. If the filesystem has an external log, it is not copied. Internal
logs are copied and any outstanding log transactions are not obfuscated if they contain
names.
xfs_metadump is a shell wrapper around the xfs_db(8) metadump command.
SEE ALSO
xfs_repair(8), xfs_mdrestore(8), xfs_freeze(8), xfs_db(8), xfs_copy(8), xfs(5)
BUGS
Email bug reports to linux-xfs@vger.kernel.org.
xfs_metadump(8)