Netgear ReadyNAS HDD size question

[smakme7757]

Ok, so i got a Netgear ReadyNAS Ultra v4 (RNDU4000) on the way and I'm wondering how these disks would work in the system.

2x 2TB (Samsung HD 204UI 5400RPM)
2x 640GB (WD Black 7200RPM)

Now I'm more interested in how the capacity is calculated. I'll presume all the drives will spin as fast as the slowest drive (5400RPM), but how does the ready NAS organize the space.

So far i understand that using 2x 2TB drives will give me 2TB storage + redundancy which is ok, but would adding the 2 640GB drives be of any use or would it just decrease the over all capacity? i.e Does the smallest disk govern the size of all disks? Or can the unit increase available space providing it has matching pairs of disks?

Thanks people.

 

[Spikesoldier]

you should be able to run two RAID1 mirrors resulting in 2TB and 640GB volumes with redundancy.

 

[smakme7757]

you should be able to run two RAID1 mirrors resulting in 2TB and 640GB volumes with redundancy.

Ah that wouldn't be too bad at all, the price of 2TB drives are much higher than when i purchased the two Samsung drives last year otherwise i would have got 2 more 2TB drives.

Thank you for the reply.