Manual partitioning: size symbol ambiguity

[Gabriel]

It is not obvious what size symbol's one can use when using a manual partition besides for the example "G". It took me several attempts to use M instead of MB. In hindsight it's a little more obvious as G == GB. I do not know if anything else is acceptable besides G or M.

Potential solutions:

1. Provide some type of help/guidance when something makes a mistake. Currently the error says "'500MB' is not valid input'.

2. Accept more symbols, examples:

 * M or MB
 * G or GB
 * T or TB
 * P or PB

3. Both - better guidance / error messaging and accepting more symbols.

[Michael Hudson-Doyle (mwhudson)]

Yeah, we should accept MB etc too. And write error messages that explain how to fix the problem when we can.