My network hard drive box had two 2TB hard drives in it, acting as mirrors of each other, but was down to 60GB free, and unless I wanted to start deleting data I needed to expand it.
Fortunately, this turned out to be as easy as "Buy new 2TB hard drive, slide it into casing, leave box alone while it automatically adds it to the RAID pool*, have 2TB free".
It's great when things just work.
*Synology's NAS OS is great for this - it will even allow you to add larger hard drives to the RAID and attempt to use it sensibly (explanation). Well worth the cash.
Original post on Dreamwidth - there are comments there.
- I love smart technology