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xfs_fsr(8)                           System Manager's Manual                           xfs_fsr(8)

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  num‐
       ber 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/.fsr‐
       last_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   If  the  information  found  here is somehow inconsistent or out of date it is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/.fsr‐
       last_xfs nor does it run for a fixed time interval.  It makes one pass through each speci‐
       fied 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 tem‐
       porary 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  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 direc‐
       tory 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)

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