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

Posted on in Categories last updated March 22, 2006

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

Output:

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

3 comment

  1. 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.

    1. Ext3 is more protected against fragmentation, but it may also occur.
      Rare, but possible. I’ve experienced once with big data base files.

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