ReadyNAS Pro with 6 2TB drives to 6 3TB with Dual Redun

camelxx wrote:
You mention label disk order when pulling out old drives. Is this in case I want to go back to the old set up, obviously needing to keep drives in their original RAID physical order?

Yes. If all disks are fine the order might not matter but best to keep the ordering the same.

camelxx wrote:
Right now I'm using 8 tb of my 9+ tb. What will be the size of with dual Redundancy with (3 Tb drives) with 4 drives? 5 drives? and 6 drives?

Very roughly:

4x3TB drives about 5.4TB
5x3TB drives around 8TB
With 6x3TB drives it'd be around 11TB.

Remember that 1TB = 1024^4 bytes whereas disk manufacturer says 1TB = 1000^4 bytes. So a so-called "3TB" disk actually has a capacity less than 3TB as far as the NAS is concerned. There are of course overheads as well.

Taking a look at X-RAID2 dual-redundancy expansion paths may also help (note this was written before there was the option to convert a single-redundant volume to a dual-redundant one: http://support.netgear.com/app/answers/detail/a_id/19044/~/converting-and-xraid2-system-to-dual-redundancy)