I think I worked out where you got the numbers from for partitioning the disk too - the 2TB disk installation blog - which I guess you must have done originally, rather than letting the Humax do it. It would have saved lots of time if you'd mentioned this, but we might not have learnt as much!
I mean, it's possible I used that blog - it was a long time ago - but honestly I don't remember doing so. I was wracking my brain just last night trying to remember how I formatted the disk originally, but could not recall anything. I genuinely concluded I must've just put the drive straight in the Humax and let that handle it.