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How do I find file fragmentation for specific file under Linux?

If you would like to find out file fragmentation information for specific file, use filefrag command that report on file fragmentation.

filefrag reports on how badly fragmented a particular file might be. It makes allowances for indirect blocks for ext2 and ext3 filesystems, but can be used on files for any filesystem.

For example see file fragmentation for /var/log/message file:

# filefrag -v /var/log/messages


Checking /var/log/messages
Filesystem type is: ef53
Filesystem cylinder groups is approximately 9448
Blocksize of file /var/log/messages is 4096
File size of /var/log/messages is 72 (1 blocks)
First block: 1841075
Last block: 1841075
/var/log/messages: 1 extent found

{ 2 comments… add one }

  • Anonymous March 22, 2006, 7:45 pm

    Nice tip. Is there also a command to defrag a file?

  • nixcraft March 23, 2006, 6:16 pm

    Use defrag (ext2, minix and xiafs filesystem defragmenter ) command. Read man page of defrag for more info.

    Ext3 file system donot need defrag as it is optimized and do not suffer from fragmentation problem in general.

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