misc/e4defrag.8.in

   1 .TH E4DEFRAG 8 "May 2009" "e4defrag version 2.0"
   2 .SH NAME
   3 e4defrag \- online defragmenter for ext4 filesystem
   4 .SH SYNOPSIS
   5 .B e4defrag
   6 [
   7 .B \-c
   8 ]
   9 [
  10 .B \-v
  11 ]
  12 .I target
  13 \&...
  14 .SH DESCRIPTION
  15 .B e4defrag
  16 reduces fragmentation of extent based file. The file targeted by
  17 .B e4defrag
  18 is created on ext4 filesystem made with "-O extent" option (see
  19 .BR mke2fs (8)).
  20 The targeted file gets more contiguous blocks and improves the file access
  21 speed.
  22 .PP
  23 .I target
  24 is a regular file, a directory, or a device that is mounted as ext4 filesystem.
  25 If
  26 .I target
  27 is a directory,
  28 .B e4defrag
  29 reduces fragmentation of all files in it. If
  30 .I target
  31 is a device,
  32 .B e4defrag
  33 gets the mount point of it and reduces fragmentation of all files in this mount
  34 point.
  35 .SH OPTIONS
  36 .TP
  37 .B \-c
  38 Get a current fragmentation count and an ideal fragmentation count, and
  39 calculate fragmentation score based on them. By seeing this score, we can
  40 determine whether we should execute
  41 .B e4defrag
  42 to
  43 .IR target .
  44 When used with
  45 .B \-v
  46 option, the current fragmentation count and the ideal fragmentation count are
  47 printed for each file.
  48 .IP
  49 Also this option outputs the average data size in one extent. If you see it,
  50 you'll find the file has ideal extents or not. Note that the maximum extent
  51 size is 131072KB in ext4 filesystem (if block size is 4KB).
  52 .IP
  53 If this option is specified,
  54 .I target
  55 is never defragmented.
  56 .TP
  57 .B \-v
  58 Print error messages and the fragmentation count before and after defrag for
  59 each file.
  60 .SH NOTES
  61 .B e4defrag
  62 does not support swap file, files in lost+found directory, and files allocated
  63 in indirect blocks. When
  64 .I target
  65 is a device or a mount point,
  66 .B e4defrag
  67 doesn't defragment files in mount point of other device.
  68 .PP
  69 Non-privileged users can execute
  70 .B e4defrag
  71 to their own file, but the score is not printed if
  72 .B \-c
  73 option is specified. Therefore, it is desirable to be executed by root user.
  74 .SH AUTHOR
  75 Written by Akira Fujita <a-fujita@rs.jp.nec.com> and Takashi Sato
  76 <t-sato@yk.jp.nec.com>.
  77 .SH SEE ALSO
  78 .BR mke2fs (8),
  79 .BR mount (8).
  80