RESIZE_FFS(8)						    BSD 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 speci-
	     fication 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 experimental, 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 consis-
     tent to start with, resize_ffs may misbehave, anything from dumping core to completely 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 layout 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.

BSD
								  January 4, 2011							       BSD