GROWFS(8) BSD System Manager's Manual GROWFS(8)NAMEgrowfs — grow size of an existing ufs file system
SYNOPSISgrowfs [-Ny] [-s size] special
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. If you are
using volumes you must enlarge them by using vinum(8). The growfs util‐
ity 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 parameters to be printed
out without actually enlarging the file system.
-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!
Determines the size of the file system after enlarging in sec‐
tors. This value defaults to the size of the raw partition spec‐
ified in special (in other words, growfs will enlarge the file
system to the size of the entire partition).
EXAMPLESgrowfs-s 4194304 /dev/vinum/testvol
will enlarge /dev/vinum/testvol up to 2GB if there is enough space in
SEE ALSObsdlabel(8), dumpfs(8), fdisk(8), ffsinfo(8), fsck(8), newfs(8),
The growfs utility first appeared in FreeBSD 4.4.
Christoph Herrmann ⟨chm@FreeBSD.org⟩
Thomas-Henning von Kamptz ⟨tomsoft@FreeBSD.org⟩
The GROWFS team ⟨growfs@Tomsoft.COM⟩
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 message. 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 provide unex‐
pected data when using -N. Therefore, this part cannot really be simu‐
lated and will be skipped in test mode.
BSD September 8, 2000 BSD