NAME

       xfs_fsr - filesystem reorganizer for XFS

SYNOPSIS

       xfs_fsr [-vdg] [-t seconds] [-p passes] [-f leftoff] [-m mtab]
       xfs_fsr [-vdg] [xfsdev | file] ...
       xfs_fsr -V

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 seconds (2 hours).

       -p passes    Number of passes before terminating global re-org.  The default is 10 passes.

       -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.

       -d           Debug.  Print even more cryptic information.

       -g           Print to syslog (default if stdout not a tty).

       -V           Prints the version number and exits.

       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       found here is somehow inconsistent or out of  date  it  is  ignored  and  reorganization  starts  at  the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)