Provided by: e2fsprogs_1.42.13-1ubuntu1_i386 bug

NAME

       e4defrag - online defragmenter for ext4 filesystem

SYNOPSIS

       e4defrag [ -c ] [ -v ] target ...

DESCRIPTION

       e4defrag  reduces fragmentation of extent based file. The file targeted
       by e4defrag is created on ext4 filesystem made with "-O extent"  option
       (see  mke2fs(8)).   The  targeted  file gets more contiguous blocks and
       improves the file access speed.

       target is a regular file, a directory, or a device that is  mounted  as
       ext4   filesystem.    If   target  is  a  directory,  e4defrag  reduces
       fragmentation of all files in it. If target is a device, e4defrag  gets
       the  mount  point  of it and reduces fragmentation of all files in this
       mount point.

OPTIONS

       -c     Get a current fragmentation count  and  an  ideal  fragmentation
              count,  and  calculate  fragmentation  score  based  on them. By
              seeing this score, we can determine whether  we  should  execute
              e4defrag  to  target.   When  used  with  -v option, the current
              fragmentation  count  and  the  ideal  fragmentation  count  are
              printed for each file.

              Also this option outputs the average data size in one extent. If
              you see it, you'll find the file has ideal extents or not.  Note
              that  the maximum extent size is 131072KB in ext4 filesystem (if
              block size is 4KB).

              If this option is specified, target is never defragmented.

       -v     Print error messages and  the  fragmentation  count  before  and
              after defrag for each file.

NOTES

       e4defrag does not support swap file, files in lost+found directory, and
       files allocated in indirect blocks. When target is a device or a  mount
       point,  e4defrag  doesn't  defragment  files  in  mount  point of other
       device.

       Non-privileged users can execute e4defrag to their own  file,  but  the
       score  is  not  printed  if  -c  option  is specified. Therefore, it is
       desirable to be executed by root user.

AUTHOR

       Written by Akira Fujita <a-fujita@rs.jp.nec.com> and Takashi  Sato  <t-
       sato@yk.jp.nec.com>.

SEE ALSO

       mke2fs(8), mount(8).