Extending a pool leaves the user wondering whether or not they will lose all of their data
See attached screenshot.
1. have 6 (virtual) disks
2. create a RAIDZ1 using 3 disks
3.in the extend a pool screen, add 3 disks to stripe in an identical raidz vdev
There are several issues in the screenshot that leaves the reader wondering.
In my example, the RAIDZ1 already had a capacity of 28GB. Extending the pool shows the new capacity as 28G and promises to destroy the data on the disks. Fortunately the backend does the right thing and the resulting pool increases to 56G, but you would never be able to tell that from this screen.
1. Show the new "extended" capacity.
2. Clarify the warning message to either indicate that the added disks will lose data, but not the pool itself.