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
.
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 consistent 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
NetBSD2.0.
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.