xfs_copy - copy the contents of an XFS filesystem
xfs_copy [ -bd ] [ -L log ] source target1 [
target2 ... ]
xfs_copy copies an XFS filesystem to one or more targets in parallel (see
xfs(5)). The first (source) argument must be the pathname of the
device or file containing the XFS filesystem. The remaining arguments specify
one or more target devices or file names. If the pathnames specify
devices, a copy of the source XFS filesystem is created on each device. The
target can also be the name of a regular file, in which case an image
of the source XFS filesystem is created in that file. If the file does not
exist, xfs_copy creates the file. The length of the resulting file is
equal to the size of the source filesystem. However, if the file is created on
an XFS filesystem, the file consumes roughly the amount of space actually used
in the source filesystem by the filesystem and the XFS log. The space saving
is because xfs_copy seeks over free blocks instead of copying them and
the XFS filesystem supports sparse files efficiently.
xfs_copy should only be used to copy unmounted filesystems,
read-only mounted filesystems, or frozen filesystems (see
xfs_freeze(8)). Otherwise, the generated filesystem(s) would be
inconsistent or corrupt.
xfs_copy does not alter the source filesystem in any way.
Each new (target) filesystem is identical to the original filesystem except
that new filesystems each have a new unique filesystem identifier (UUID).
Therefore, if both the old and new filesystems will be used as separate
distinct filesystems, xfs_copy or
xfsdump(8)/xfsrestore(8) should be used to generate the new
filesystem(s) instead of dd(1) or other programs that do
block-by-block disk copying.
xfs_copy uses synchronous writes to ensure that write
errors are detected.
xfs_copy uses pthreads(7) to perform simultaneous
parallel writes. xfs_copy creates one additional thread for each
target to be written. All threads die if xfs_copy terminates or
xfs_copy reports errors to both stderr and in more detailed form
to a generated log file whose name is of the form
/var/tmp/xfs_copy.log.XXXXXX or a log file specified by the -L
option. If xfs_copy detects a write error on a target, the copy of that
one target is aborted and an error message is issued to both stderr and the
log file, but the rest of the copies continue. When xfs_copy
terminates, all aborted targets are reported to both stderr and the log
- Create a duplicate (true clone) filesystem. This should be done only if
the new filesystem will be used as a replacement for the original
filesystem (such as in the case of disk replacement).
- The buffered option can be used to ensure direct IO is not attempted to
any of the target files. This is useful when the filesystem holding the
target file does not support direct IO.
- -L log
- Specifies the location of the log if the default location of
/var/tmp/xfs_copy.log.XXXXXX is not desired.
- Prints the version number and exits.
If all targets abort or if there is an error reading the source
filesystem, xfs_copy immediately aborts.
xfs_copy returns an exit code of 0 if all targets are
successfully copied and an exit code of 1 if any target fails.
When moving filesystems from one disk to another, if the original filesystem is
significantly smaller than the new filesystem, and will be made larger, we
recommend that mkfs.xfs(8) and xfsdump(8)/xfsrestore(8)
be used instead of using xfs_copy and xfs_growfs(8). The
filesystem layout resulting from using xfs_copy/xfs_growfs is
almost always worse than the result of using
mkfs.xfs/xfsdump/xfsrestore but in the case of small
filesystems, the differences can have a significant performance impact. This
is due to the way xfs_growfs(8) works, and not due to any shortcoming
in xfs_copy itself.
xfs_copy does not copy XFS filesystems that have a real-time section or
XFS filesystems with external logs. In both cases, xfs_copy aborts with
an error message.