How to resize ZFS in FreeNAS

One of the frequently asked questions regarding ZFS. Is it possible to resize a RAIDZ, RAIDZ2 or MIRRORED ZPOOL?

The answer is a littlebit complicated...
If you want to change the 'geometry' of the ZPOOL (for example: change from a mirrored pool to a raidz, or simply add a disk to a raidz, or change from raidz to raidz2) then the answer is no.

But it is possible to change the disks of a pool with bigger ones and use the space.

Here is what I've tested with a FreeNAS 0.7 (rev 3514) installed as a Virtual Machine.