"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!
-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, growfs will enlarge the file system to the size of the entire partition).