Sun won't tell you, BUT...

Many people use Veritas Volume Manager to manage storage on big Solaris systems. You can use Veritas to expand the size of Veritas volumes, but you also have to expand the ufs file system that's on top of the device.

You might wonder how Veritas' GUI can expand Solaris ufs file systems, online, without losing data, when Sun support will tell you it's not possible. Well, you just have to know the "undocumented" -M option to mkfs to make it happen.

# /usr/lib/fs/ufs/mkfs -F ufs -M [mountpoint] [vx rdsk device] [volsize from vxprint]

Be careful. If you forget the -M option, you will end up with a brand-new, EMPTY file system.