If you are upgrading the software on the v6 boxes then both boxes will act like a full v360 so you will have access to both hard drives, the benefits are if one box goes down you will only loose half of the recordings and not all of them, you will have twice as much storage i.e. 2Tb instead of 1Tb, both boxes will have a large pause instead of the mini limited at around 3/4 minutes.
As a side note beware that the upgrade of software will wipe everything from both drives, recording, series links etc.
If you are upgrading on the Ultimate Oomph package you will get new boxes, and will get one v360 and one v360 mini.
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