# phpman > man > e4defrag(8)

[E4DEFRAG(8)](https://www.chedong.com/phpMan.php/man/E4DEFRAG/8/markdown)                            System Manager's Manual                           [E4DEFRAG(8)](https://www.chedong.com/phpMan.php/man/E4DEFRAG/8/markdown)



## NAME
       e4defrag - online defragmenter for ext4 file system

## SYNOPSIS
       **e4defrag** [ **-c** ] [ **-v** ] _target_ ...

## DESCRIPTION
       **e4defrag** reduces fragmentation of extent based file. The file targeted by **e4defrag** is created
       on ext4 file system made with "-O extent" option (see [**mke2fs**(8)](https://www.chedong.com/phpMan.php/man/mke2fs/8/markdown)).   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 file system.  If
       _target_ is a directory, **e4defrag** reduces fragmentation of all files in it. If _target_ is a  de‐
       vice,  **e4defrag**  gets  the  mount  point of it and reduces fragmentation of all files in this
       mount point.

## OPTIONS
### -c
              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  fragmenta‐
              tion 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 file system (if block size is 4KB).

              If this option is specified, _target_ is never defragmented.

### -v
              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.

       It is safe to run e4defrag on a file while it is actively  in  use  by  another  application.
       Since  the contents of file blocks are copied using the page cache, this can result in a per‐
       formance slowdown to both e4defrag and the application due to contention  over  the  system's
       memory and disk bandwidth.

       If  the file system's free space is fragmented, or if there is insufficient free space avail‐
       able, e4defrag may not be able to improve the file's fragmentation.

       Non-privileged users can execute **e4defrag** to their own file, but the score is not printed  if
### -c

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

## SEE ALSO
       [**mke2fs**(8)](https://www.chedong.com/phpMan.php/man/mke2fs/8/markdown), [**mount**(8)](https://www.chedong.com/phpMan.php/man/mount/8/markdown).




e4defrag version 2.0                          May 2009                                   [E4DEFRAG(8)](https://www.chedong.com/phpMan.php/man/E4DEFRAG/8/markdown)