| Theodore Ts'o | 4836459 | 2009-07-09 14:29:12 -0400 | [diff] [blame] | 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 |
| Kazuya Mio | 77e72e2 | 2010-12-13 09:59:07 -0500 | [diff] [blame] | 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 |
| Theodore Ts'o | 4836459 | 2009-07-09 14:29:12 -0400 | [diff] [blame] | 41 | .B e4defrag |
| 42 | to |
| 43 | .IR target . |
| 44 | When used with |
| 45 | .B \-v |
| Kazuya Mio | 77e72e2 | 2010-12-13 09:59:07 -0500 | [diff] [blame] | 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). |
| Theodore Ts'o | 4836459 | 2009-07-09 14:29:12 -0400 | [diff] [blame] | 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 | |