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NAME

       xfs_fsr - filesystem reorganizer for XFS

SYNOPSIS

       xfs_fsr [-v] [-t seconds] [-f leftoff] [-m mtab]
       xfs_fsr [-v] [xfsdev | file] ...

DESCRIPTION

       xfs_fsr is applicable only to XFS filesystems.

       xfs_fsr   improves   the  organization  of  mounted  filesystems.   The
       reorganization algorithm operates on one file at a time, compacting  or
       otherwise  improving  the layout of the file extents (contiguous blocks
       of file data).

       The following options are accepted by xfs_fsr.   The  -m,  -t,  and  -f
       options  have  no  meaning if any filesystems or files are specified on
       the command line.

       -m mtab      Use this file for the list of filesystems  to  reorganize.
                    The default is to use /etc/mtab.

       -t seconds   How long to reorganize.  The default is 7200 (2 hours).

       -f leftoff   Use  this  file  instead  of /var/tmp/.fsrlast to read the
                    state of where to start and as the file to store the state
                    of where reorganization left off.

       -v           Verbose.   Print cryptic information about each file being
                    reorganized.

       When invoked with no arguments xfs_fsr reorganizes all regular files in
       all mounted filesystems.  xfs_fsr makes many cycles over /etc/mtab each
       time making a single pass over each XFS  filesystem.   Each  pass  goes
       through  and selects files that have the largest number of extents.  It
       attempts to defragment the top 10% of these files on each pass.

       It runs for up to two hours after which it records the filesystem where
       it  left off, so it can start there the next time.  This information is
       stored in the file /var/tmp/.fsrlast_xfs.   If  the  information  found
       here  is  somehow  inconsistent  or  out  of  date  it  is  ignored and
       reorganization starts at the beginning of the first filesystem found in
       /etc/mtab.

       xfs_fsr  can  be  called  with one or more arguments naming filesystems
       (block device name), and files to reorganize.   In  this  mode  xfs_fsr
       does  not  read  or  write  /var/tmp/.fsrlast_xfs nor does it run for a
       fixed time interval.  It makes one pass through each specified  regular
       file  and  all  regular  files in each specified filesystem.  A command
       line name referring to  a  symbolic  link  (except  to  a  file  system
       device),  FIFO,  or UNIX domain socket generates a warning message, but
       is otherwise ignored.  While traversing the filesystem these  types  of
       files are silently skipped.

FILES

       /etc/mtab            contains    default   list   of   filesystems   to
                            reorganize.
       /var/tmp/.fsrlast_xfs
                            records the state where reorganization left off.

SEE ALSO

       xfs_fsr(8), mkfs.xfs(8), xfs_ncheck(8), xfs(5).

NOTES

       xfs_fsr improves the layout of extents for each  file  by  copying  the
       entire  file  to  a  temporary location and then interchanging the data
       extents of the target and temporary files in an  atomic  manner.   This
       method  requires  that  enough free disk space be available to copy any
       given file and that the space be  less  fragmented  then  the  original
       file.   It also requires the owner of the file to have enough remaining
       filespace quota to do the copy  on  systems  running  quotas.   xfs_fsr
       generates  a  warning message if space is not sufficient to improve the
       target file.

       A temporary file used in improving a file given on the command line  is
       created in the same parent directory of the target file and is prefixed
       by the string ’.fsr’.  The temporary files used in improving an  entire
       XFS  device  are stored in a directory at the root of the target device
       and use the same naming scheme.  The temporary files are unlinked  upon
       creation so data will not be readable by any other process.

       xfs_fsr  does not operate on files that are currently mapped in memory.
       A ’file busy’ error can be seen for these files  if  the  verbose  flag
       (-v) is set.

       An  entry  in  /etc/mtab or the file specified using the -m option must
       have the rw option specified for read and write access.  If this option
       is  not  present,  then  xfs_fsr skips the filesystem described by that
       line.  See the fstab(5) reference page for more details.

       In general we do  not  foresee  the  need  to  run  xfs_fsr  on  system
       partitions  such  as  /,  /boot  and  /usr as in general these will not
       suffer from fragmentation.  There are also  issues  with  defragmenting
       files lilo(8) uses to boot your system.  Should these files be moved by
       xfs_fsr then you must rerun lilo before you reboot or you may  have  an
       unbootable system.

                                                                    xfs_fsr(8)