defrag

DEFRAG(8)                   System Manager's Manual                  DEFRAG(8)



NAME
       [ex][2]defrag - defragment file systems.

SYNOPSIS
       defrag | edefrag | e2defrag | xdefrag [ -Vdnrsv ] [ -b bad-inode ] [ -i
       inode-list ] [ -p pool-size ] /dev/name


DESCRIPTION
       Defrag will reorganise data on a minix file system partition in order
       to improve the file system's performance.  Edefrag is the equivalent
       program for the extended file system.  E2defrag in its turn is designed
       for the second extended file system (versions 0.3 onwards). And the
       xdefrag program will operate on Xia FS filesystems.


       Note that unlike the fsck program, defrag MUST NOT be run on a mounted
       file system device (unless invoked with the -r (readonly) option, which
       is always safe).  Also note that if you defragment a partition
       containing a bootable kernel image, you will have to reinstall the boot
       loader for that image (since the location on disk of the image may have
       changed).

       Remember, if defrag fails to complete for any reason (including power
       glitches, kernel bugs etc.), you will be left with a terminally sick,
       and possibly completely unreadable, filesystem, so backup any valuable
       data before you start.

OPTIONS
       -V     Supply full version information.  If you are sending bug
              reports, please include this information.

       -d     Run in debugging mode.  This will not be available if disabled
              at compile-time.

       -n     No-picture more.  Disables a pseudo-graphic picture and runs
              with an old-style printf output. Note that the picture option
              requires a proper terminfo database for your terminal,
              compatible with the ncurses package.  If the picture option is
              used, -v and -s options are set automatically. Nevertheless you
              can increase amount of information output to the status line
              using several -v switches. This gives you a chance to improve
              the speed of your reading.

       -r     Readonly mode.  Defrag will scan the file system and simulate
              the job of defragmentation, but will not write to the file
              system.  This can be used for debugging or testing.  It may also
              be used to find out how much work defrag will have to do, in
              order to choose a sensible pool-size

       -s     Summarise file system information and defrag performance
              statistics.

       -v     Verbose - gives a progress report as defragmentation proceeds.
              If -v is given twice, then a more detailed report is supplied.
              The fullest report, when -v is given three times, also reports
              the inode priority list as it is read.

       -b bad-inode
              Indicate which inode stores the badblock list on the filesystem
              being defragmented.  This should be an inode whose data blocks
              are all bad blocks.  The defragmenter will not move these
              blocks, and will prevent any other data from being placed there.

              The default for edefrag is -b 2, since mkefs always creates a
              bad block inode at inode 2.  The minix filesystem does not have
              a bad block inode by default, but if you have created one,
              supply its inode number with this option.

       -i inode-list
              As of version 0.4, defrag has a new facility which allows you to
              specify how to reorganise the data on your disk.  The inode-list
              is an optional file giving a priority between -100 and 100 to
              each inode in the filesystem.  Higher priorities will be
              allocated nearer the beginning of the disk than lower (more
              negative) priorities.  Two inodes of equal priority will be
              allocated in the same sequence they had originally on the
              filesystem, to minimise file movement.  All inodes have a
              default priority of zero if they are ommitted from the file or
              if no -i option is given.

              The file inode-list should contain a series of lines containing
              either a single number (which will be interpreted as an inode
              number), or a number prefixed immediately by an equals sign
              (which will be interpreted as a priority to be applied to the
              subsequent inode numbers).

       -p number
              Selects the number of (1KB) buffers allocated to the
              defragmenter's buffer pool.  These buffers are used when
              relocating data, so the more buffers allocated, the more
              efficient the relocation process.  The number you choose will
              depend on how much physical and virtual memory you have
              available.

BUGS
       Maybe, but then that's why you backed up your data first, isn't it?

AUTHORS
       Written by Stephen Tweedie.  Adaptation for the xia, ext2 filesystem
       and the picture option are done by Alexey Vovenko.  Much of the initial
       version was developed from the fsck and efsck programs by Linus
       Torvalds and Remy Card.

       Send bug reports, fixes, improvements, comments and fan-mail to
       sct@dcs.ed.ac.uk.



                           Version 0.6   22 May 1994                 DEFRAG(8)