xfs_fsr(8)                                                                                                            xfs_fsr(8)



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       out of date it is ignored and reorganization starts at the beginning of the first filesystem found in /etc/mtab.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  refer-
       ring 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  inter-
       changing  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  cre-
       ation 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)  ref-
       erence 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)