growfs(8) grow size of an existing ufs file system


[-Ny [-s size ] ] special


The utility extends the newfs(8) program. Before starting 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 . If you are using volumes you must enlarge them by using vinum(8). The utility extends the size of the file system on the specified special file. Currently 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 . In fact, you can only increase the size of the file system. Use tunefs(8) for other changes.

The following options are available:

``Test mode'' Causes the new file system parameters to be printed out without actually enlarging the file system.
``Expert mode'' Usually 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 enlarging in sectors. This value defaults to the size of the raw partition specified in special (in other words, will enlarge the file system to the size of the entire partition).


growfs -s 4194304 /dev/vinum/testvol

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


The utility first appeared in Fx 4.4 .


An Christoph Herrmann Aq [email protected] An Thomas-Henning von Kamptz Aq [email protected] An The GROWFS team Aq [email protected]


The utility works starting with Fx 3.x. There may be cases on Fx 3.x only, when does not recognize properly whether or not the file system is mounted and exits with an error message. Then please use -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 Fx 3.x this will cause problems with fsck(8) afterwards. So fsck(8) needs to be patched if you want to use for Fx 3.x. This patch is already integrated in Fx starting with Fx 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 writes this critical structure to disk and reads it again later for doing more updates. This read operation will provide unexpected data when using -N Therefore, this part cannot really be simulated and will be skipped in test mode.