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   If  the  information found here is somehow inconsistent or out of
       date it is ignored and reorganization starts at the  beginning  of  the  first  filesystem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 than 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.

       Files marked as no-defrag will be  skipped.  The  xfs_io(8)  chattr  command  with  the  f
       attribute  can  be  used  to  set  or  clear this flag. Files and directories created in a
       directory with the no-defrag flag will inherit the attribute.

       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. It is  recommended  that  these
       files should be flagged as no-defrag with the xfs_io(8) chattr command. 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)