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diff --git a/misc/e4defrag.8.in b/misc/e4defrag.8.in new file mode 100644 index 0000000..53d7f17 --- /dev/null +++ b/misc/e4defrag.8.in @@ -0,0 +1,90 @@ +.TH E4DEFRAG 8 "May 2009" "e4defrag version 2.0" +.SH NAME +e4defrag \- online defragmenter for ext4 file system +.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 file system 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 file system. +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 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 +.B e4defrag +to +.IR target . +When used with +.B \-v +option, the current fragmentation count and the ideal fragmentation count are +printed for each file. +.IP +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). +.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 +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 performance slowdown to both e4defrag +and the application due to contention over the system's memory and disk +bandwidth. +.PP +If the file system's free space is fragmented, or if there is +insufficient free space available, e4defrag may not be able +to improve the file's fragmentation. +.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 <a-fujita@rs.jp.nec.com> and Takashi Sato +<t-sato@yk.jp.nec.com>. +.SH SEE ALSO +.BR mke2fs (8), +.BR mount (8). + |