Provided by: ext2resize_1.1.19-3_i386 bug

NAME

       ext2prepare - ext2 filesystem resizing preparation tool

SYNOPSIS

       ext2prepare [-d] [-f] [-q] [-v] [-V] device size[b|K|M|G|T]]

DESCRIPTION

       The ext2prepare command modifies an unmounted ext2 filesystem on device
       so that ext2online(8) program can later resize the  mounted  filesystem
       to  be  at least as large as size although the actual maximum size will
       be some  larger  multiple  of  various  filesystem  parameters.   While
       ext2prepare  must  be  run  on an unmounted filesystem, device does not
       have to currently be as large  as  size.   This  allows  one  to  later
       increase  the  size of device and do the resize while the filesystem is
       mounted.

       If the size parameter does not have a modifier, it will be taken to  be
       in  ext2  filesystem  blocks  (which  can  be  1k,  2k,  or  4k  -  use
       dumpe2fs(8) to find out more information about the current filesystem).
       The  modifiers  b,  K,  M,  G, or T mean the size parameter is given in
       512-byte blocks, kilo-, mega-, giga-, or terabytes respectively.

       The ext2prepare program does not change the size of the actual  device.
       If  you wish to enlarge a filesystem, you must make sure you expand the
       underlying device first.  This can be done online for  Logical  Volumes
       by  using  lvextend(8) from the LVM package, or possibly via md or RAID
       facilities in the hardware if you are not using partitions.  It is  not
       possible  to  do this by using the fdisk(8) family of tools to extend a
       partition while it is mounted (at least the author has not been able to
       successfully do this).

       Because  of  the  original  design  of the ext2 filesystem did not have
       online resizing in mind, there are certain limitations to the amount of
       resizing  that  can  be  done  while  the filesystem is mounted, if you
       haven’t done any preparation for the resize.  The  default  block  size
       for  ext2  was  1k  blocks  until  v1.15  of e2fsprogs (1999), where it
       changed to 4k blocks for filesystems larger than 512MB.

       With no filesystem preparation, it is always possible to resize to  the
       next  256MB  boundary for 1k filesystems, the next 2GB boundary for for
       2k filesystems, and the next 16GB  boundary  for  4k  filesystems.   By
       using  ext2prepare  on  an  unmounted  filesystem,  it  is possible for
       ext2online(8) to increase the size of a mounted ext2 filesystem  to  at
       least  the  given size by reserving blocks for group descriptors within
       the  ext2  filesystem  structure.   ext2prepare  does  this  by  moving
       metadata  blocks while the filesystem is unmounted, and then allocating
       the freed blocks to a reserved inode so that  ext2online(8)  can  later
       use  these blocks to safely enlarge the filesystem while the filesystem
       is in use.

OPTIONS

       -d, --debug
              Turn on debugging messages.

       -f, --force
              Force preparation without first checking the filesystem state.

       -q, --quiet
              Do not print anything but error messages.

       -v, --verbose
              Turn on normal verbose status messages.

       -V, --version
              Print the version number and exit.

RETURN VALUES

       0    Resizing successful

       1    Error in options or command-line parameters.

       2    Error while preparing filesystem.

EXAMPLES

       The following example shows  how  to  test  ext2prepare  with  a  spare
       partition.   First  a filesystem of 32MB is created on the device.  The
       filesystem is then prepared to grow to a maximum size of 10GB, mounted,
       and  the size is verified.  The filesystem is then extended to fill the
       device (the default action when no size is given), and the new size  is
       verified.

            mke2fs /dev/vg0/lvtest 32768
            ext2prepare /dev/vg0/lvtest 10G
            mkdir /mnt/test
            mount -o debug,check=strict /dev/vg0/lvtest /mnt/test
            df /mnt/test
            ext2online -d -v /dev/vg0/lvtest
            df /mnt/test

       By using the debug and check=strict options to mount, as well as the -d
       and -v options to  ext2prepare,  we  will  see  the  user-space  status
       messages, and the kernel messages will be logged by syslog.

WARNING

       Note that resizing a mounted filesystem is inherently dangerous and may
       corrupt filesystems, although no errors resulting  in  data  loss  have
       ever  been  reported  to  the author.  In theory online resizing should
       work fine with arbitrarily large filesystems, but it has not  yet  been
       tested  by  the  author  on  a  filesystem  larger than 11GB.  Use with
       caution.  Backups are always a good idea, because your disk may fail at
       any time, you delete files by accident, or your computer is struck by a
       meteor.

AUTHOR

       The   ext2prepare   program   was    written    by    Andreas    Dilger
       <adilger@clusterfs.com>  using  the  ext2  resizing  tools developed by
       Lennert Buytenhek <buytenh@gnu.org>.  The ext2online kernel patches are
       available    as    part    of    the    GNU   ext2resize   package   at
       <http://sourceforge.org/projects/ext2resize/>.

BUGS

       Because ext2prepare uses a reserved inode to store blocks needed for  a
       future  resize  (so  that  they  can’t  be accidentally used by another
       program), e2fsck(8) needs to be slightly modified  to  understand  this
       new  reserved inode.  If an unmodified e2fsck(8) is run on a filesystem
       that has been changed with ext2prepare,  it  will  complain  about  the
       reserved  inode  and free all of the blocks associated with this inode.
       If this happens, it will not be possible to resize the filesystem  past
       the default limits given previously.  However, the filesystem itself is
       not affected in any way by these events.  The  ext2resize  programs  do
       not work on big-endian machines (Alpha, SPARC, PPC, etc).

COPYRIGHT

       ext2prepare is (C) Copyright 1999, 2000, 2001 by Andreas Dilger and may
       be distributed under the terms of the GNU General Public License.

SEE ALSO

       dumpe2fs(8) ext2online(8) ext2resize(8) e2fsck(8) lvextend(8)