growfs (8)

Name

growfs - grow size of an existing ufs file system

Synopsis

growfs [-Ny] [-s size] special

Description

The growfs utility extends the newfs(8) program. Before starting growfs
the disk must be labeled to a bigger size using bsdlabel(8) .

If you wish

to grow a file system beyond the boundary of the slice it resides in, you
must re-size the slice using fdisk(8) before running growfs.

using volumes you must enlarge them by using vinum(8) . The growfs utility
extends the size of the file system on the specified special file.
Currently growfs can only enlarge unmounted file systems.

Do not try

enlarging a mounted file system, your system may panic and you will not
be able to use the file system any longer. Most of the newfs(8) options
cannot be changed by growfs. In fact, you can only increase the size of
the file system. Use tunefs(8) for other changes.

The following options are available:

-N: ‘‘Test mode’’. Causes the new file system parame ters to be printed out without actually enlarging the file sys tem.
-y: ‘‘Expert mode’’. Usually growfs will ask you if you took a backup of your data before and will do some tests whether special is currently mounted or whether there are any active snapshots on the file system specified. This will be suppressed.

So use this

option with great care!

-s size: Determines the size of the file system after enlarg ing in sectors. This value defaults to the size of the raw partition specified in special (in other words, growfs will en large the file system to the size of the entire partition).

Examples

growfs -s 4194304 /dev/vinum/testvol

will enlarge /dev/vinum/testvol up to 2GB if there is enough space in
/dev/vinum/testvol.

History

The growfs utility first appeared in FreeBSD 4.4.

Authors

Christoph Herrmann <chm@FreeBSD.org>
Thomas-Henning von Kamptz <tomsoft@FreeBSD.org> The GROWFS team <growfs@Tomsoft.COM>

Bugs

The growfs utility works starting with FreeBSD 3.x. There may be cases
on FreeBSD 3.x only, when growfs does not recognize properly whether or

not: the file system is mounted and exits with an error mes sage. Then please use growfs -y if you are sure that the file system is not mounted. It is also recommended to always use fsck(8) after enlarging (just to be on the safe side).

For enlarging beyond certain limits, it is essential to have some free
blocks available in the first cylinder group. If that space is not
available in the first cylinder group, a critical data structure has to
be relocated into one of the new available cylinder groups.

On FreeBSD

3.x this will cause problems with fsck(8) afterwards. So fsck(8) needs
to be patched if you want to use growfs for FreeBSD 3.x.

This patch is

already integrated in FreeBSD starting with FreeBSD 4.4. To avoid an
unexpected relocation of that structure it is possible to use ffsinfo -g
0 -l 4 on the first cylinder group to verify that nbfree in the CYLINDER
SUMMARY (internal cs) of the CYLINDER GROUP cgr0 has enough blocks. As a
rule of thumb for default file system parameters one block is needed for
every 2 GB of total file system size.

Normally growfs writes this critical structure to disk and reads it again
later for doing more updates. This read operation will pro vide unexpected
data when using -N. Therefore, this part cannot re ally be simulated
and will be skipped in test mode.