Ubuntu Manpage: xfs_copy - copy the contents of an XFS filesystem

Provided by: xfsprogs_6.8.0-2.2ubuntu1.1_amd64

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
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 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
       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.

NOTES

       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.

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.