Manpage of ext4 online defrag command

ext4: online defrag -- Ext4 online defrag command manpage

From: Akira Fujita <[email protected]>

Following is e4defrag command manpage. Please use nroff -man e4defrag.8 | less to view.

---
.TH E4DEFRAG 8 "May 2009" "e4defrag version 2.0"
.SH NAME
e4defrag \- online defragmenter for ext4 filesystem
.SH SYNOPSIS
.B e4defrag
[
.B \-c
]
[
.B \-v
]
.I target
\&...
.SH DESCRIPTION
.B e4defrag
reduces fragmentation of extent based file. The file targeted by .B e4defrag
is created on ext4 filesystem made with "-O extent" option (see .BR mke2fs (8)).
The targeted file gets more contiguous blocks and improves the file access speed.
.PP
.I target
is a regular file, a directory, or a device that is mounted as ext4 filesystem. If
.I target
is a directory,
.B e4defrag
reduces fragmentation of all files in it. If
.I target
is a device,
.B e4defrag
gets the mount point of it and reduces fragmentation of all files in this mount point.
.SH OPTIONS
.TP
.B \-c
Get the fragmentation count and calculate fragmentation score based on it before and after defrag. By seeing this score, we can determine whether we should execute
.B e4defrag
to
.IR target .
When used with
.B \-v
option, the fragmentation count before and after defrag is printed for each file.
.IP
If this option is specified,
.I target
is never defragmented.
.TP
.B \-v
Print error messages and the fragmentation count before and after defrag for each file.
.SH NOTES
.B e4defrag
does not support swap file, files in lost+found directory, and files allocated in indirect blocks. When
.I target
is a device or a mount point,
.B e4defrag
doesn't defragment files in mount point of other device.
.PP
Non-privileged users can execute
.B e4defrag
to their own file, but the score is not printed if
.B \-c
option is specified. Therefore, it is desirable to be executed by root user. .SH AUTHOR
Written by Akira Fujita <[email protected]> and Takashi Sato <[email protected]>.
.SH SEE ALSO
.BR mke2fs (8),
.BR mount (8).