1E4DEFRAG(8)                 System Manager's Manual                E4DEFRAG(8)
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NAME

6       e4defrag - online defragmenter for ext4 filesystem
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SYNOPSIS

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

12       e4defrag  reduces fragmentation of extent based file. The file targeted
13       by e4defrag is created on ext4 filesystem made with "-O extent"  option
14       (see  mke2fs(8)).   The  targeted  file gets more contiguous blocks and
15       improves the file access speed.
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17       target is a regular file, a directory, or a device that is  mounted  as
18       ext4 filesystem.  If target is a directory, e4defrag reduces fragmenta‐
19       tion of all files in it. If target is a device, e4defrag gets the mount
20       point of it and reduces fragmentation of all files in this mount point.
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OPTIONS

23       -c     Get  a  current  fragmentation  count and an ideal fragmentation
24              count, and calculate fragmentation score based on them. By  see‐
25              ing  this  score,  we  can  determine  whether we should execute
26              e4defrag to target.  When used with -v option, the current frag‐
27              mentation  count  and  the ideal fragmentation count are printed
28              for each file.
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30              Also this option outputs the average data size in one extent. If
31              you  see it, you'll find the file has ideal extents or not. Note
32              that the maximum extent size is 131072KB in ext4 filesystem  (if
33              block size is 4KB).
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35              If this option is specified, target is never defragmented.
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37       -v     Print  error  messages  and  the  fragmentation count before and
38              after defrag for each file.
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NOTES

41       e4defrag does not support swap file, files in lost+found directory, and
42       files  allocated in indirect blocks. When target is a device or a mount
43       point, e4defrag doesn't  defragment  files  in  mount  point  of  other
44       device.
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46       Non-privileged  users  can  execute e4defrag to their own file, but the
47       score is not printed if -c option is specified. Therefore, it is desir‐
48       able to be executed by root user.
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AUTHOR

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

55       mke2fs(8), mount(8).
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60e4defrag version 2.0               May 2009                        E4DEFRAG(8)
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