RESIZE_FFS(8)           NetBSD System Manager's Manual           RESIZE_FFS(8)

NAME
     resize_ffs -- resize a file system on disk or in a file

SYNOPSIS
     resize_ffs [-y] [-s size] special

DESCRIPTION
     resize_ffs resizes a file system.  special is the name of the raw disk
     device or file where the file system resides.  resize_ffs can both grow
     and shrink file systems.  When growing, the disk device must of course be
     large enough to contain the new file system; resize_ffs simply extends
     the file system data structures into the new space.  When shrinking,
     resize_ffs assumes this.  resize_ffs has to copy anything that currently
     resides in the space being shrunk away; there must be enough space free
     on the file system for this to succeed.  If there isn't, resize_ffs will
     complain and exit; when this happens, it attempts to always leave the
     file system in a consistent state, but it is probably a good idea to
     check the file system with fsck(8).

     If no -s option is provided, resize_ffs will grow the file system to the
     underlying device size which is determined from special.

     The options are as follows:

     -s      Specify the file system size to which the file system should be
             resized.  The size is given as the count of disk sectors, usually
             512 bytes.  It will not work correctly for file systems with
             other sector sizes.  To see the exact value, have a look at the
             disk specification or the disklabel.  Mostly used to shrink file
             systems.

     -y      Disable sanity questions made by resize_ffs.

WARNING
     Interrupting resize_ffs may leave your file system in an inconsistent
     state and require a restore from backup. It attempts to write in the
     proper order to avoid problems, but as it is still considered experimen-
     tal, you should take great care when using it.

     When resize_ffs is applied to a consistent file system, it should always
     produce a consistent file system; if the file system is not consistent to
     start with, resize_ffs may misbehave, anything from dumping core to com-
     pletely curdling the data.  It's probably wise to fsck(8) the file system
     before and after, just to be safe.  You should be aware that just because
     fsck(8) is happy with the file system does not mean it is intact.

EXIT STATUS
     resize_ffs exits with 0 on success.  Any major problems will cause
     resize_ffs to exit with the non-zero exit(3) codes, so as to alert any
     invoking program or script that human intervention is required.

EXAMPLES
           resize_ffs /dev/vg00/rlv1

     will enlarge the file system on the Logical Volume /dev/vg00/lv1 from
     Volume Group vg00 to the current device size.

SEE ALSO
     fs(5), fsck(8), newfs(8)

HISTORY
     The resize_ffs command first appeared in NetBSD 2.0.

AUTHORS
     der Mouse <mouse@rodents.montreal.qc.ca> (primary author)
     Jeff Rizzo <riz@NetBSD.org> (Byteswapped file system and UFS2 support)

     A big bug-finding kudos goes to John Kohl for finding the rotational lay-
     out bug referred to in the WARNING section above.

BUGS
     Can fail to shrink a file system when there actually is enough space,
     because it does not distinguish between a block allocated as a block and
     a block fully occupied by two or more frags.  This is unlikely to occur
     in practice; except for pathological cases, it can happen only when the
     new size is extremely close to the minimum possible.

     Has no intelligence whatever when it comes to allocating blocks to copy
     data into when shrinking.

     Doesn't currently support shrinking FFSv2 file systems.

NetBSD 6.0                      January 4, 2011                     NetBSD 6.0

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