This post was published 4 years 2 months 23 days ago. Therefore, it may well be out of date. Do not reply on the contents of this post being accurate. I plugged in a 400GB external firewire drive to perform my first Time Machine backup.
Formatted, it has 372GB available. However, TM reported the following error.
Strange, as the combined size of the data to be backed up is 334GB.
