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xfs_copy(8) System Manager's Manual xfs_copy(8)
NAME
xfs_copy - copy the contents of an XFS filesystem
SYNOPSIS
xfs_copy [ -bd ] [ -L log ] source target1 [ target2 ... ]
xfs_copy -V
DESCRIPTION
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 cre-
ates 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 copy-
ing 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 aborts.
OPTIONS
-d 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).
-b 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.
-V Prints the version number and exits.
DIAGNOSTICS
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 file.
If all targets abort or if there is an error reading the source filesystem, xfs_copy imme-
diately 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.
NOTES
When moving filesystems from one disk to another, if the original filesystem is signifi-
cantly 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.
CAVEATS
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.
SEE ALSO
mkfs.xfs(8), xfsdump(8), xfsrestore(8), xfs_freeze(8), xfs_growfs(8), xfs(5).
xfs_copy(8)
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