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).