RNPP-Future Capacity Expansion planning for Dual Redundancy

[winger]

OK, since I am no longer "pre-sales", I will post my question in this forum.

Last week as I was planning the purchase of my first set of drives for my ReadyNAS Pro Pioneer edition, I thought I understood how future capacity expansion with XRAID-2 Dual Redundancy would look like (thanks to the help over in the Presales forum) , but it has become "cloudy" again : (

*** I hope once it is clarified, this information can help others planning their first RNPP purchase.

For XRAID-2 with Dual Redundancy, are the following two options correct?
*Notes:
1) Please pay attention to the Notes column
2) One one hard drive is added to each Upgrade.
3) Assume there could up to a year between each upgrades.


Option 1
Note.............Bay1...Bay2...Bay3...Bay4...Bay5...Bay6.....Capacity.....Notes
Initial Setup....1TB....1TB....1TB....1TB........................... 2TB......Put all 4 drives in before initial Pro powerup/setup, power on, then set to DR, XR-2
Upgrade A.......1TB....1TB....1TB....1TB....1TB..................3TB......Dual Redundancy
Upgrade B.......1TB....1TB....1TB....1TB....1TB....1TB..........4TB......Dual Redundancy
Upgrade C.......2TB....1TB....1TB....1TB....1TB....1TB..........4TB......Dual Redundancy, No increase in capacity
Upgrade D.......2TB....2TB....1TB....1TB....1TB....1TB..........4TB......Dual Redundancy, No increase in capacity
Upgrade E.......2TB....2TB....2TB....1TB....1TB....1TB..........4TB......Dual Redundancy, No increase in capacity
Upgrade F.......2TB....2TB....2TB....2TB....1TB....1TB..........5TB......Dual Redundancy+start to increase capacity
Upgrade G.......2TB....2TB....2TB....2TB....2TB....1TB..........6TB......Dual Redundancy
Upgrade H.......2TB....2TB....2TB....2TB....2TB....2TB..........7TB......Dual Redundancy



Option 2
Note.............Bay1...Bay2...Bay3...Bay4...Bay5...Bay6.....Capacity.....Notes
Initial Setup....1TB....1TB....1TB....1TB........................... 2TB......Put all 4 drives in before initial Pro powerup/setup, power on, then set to DR, XR-2
Upgrade A.......1TB....1TB....1TB....1TB....2TB..................3TB......Dual Redundancy, Increase in capacity
Upgrade B.......1TB....1TB....1TB....1TB....2TB....2TB..........4TB......Dual Redundancy, Increase in capacity
Upgrade C.......2TB....1TB....1TB....1TB....2TB....2TB..........5TB......Dual Redundancy, Increase in capacity
Upgrade D.......2TB....2TB....1TB....1TB....2TB....2TB..........6TB......Dual Redundancy, Increase in capacity
Upgrade E.......2TB....2TB....2TB....1TB....2TB....2TB..........7TB......Dual Redundancy, Increase in capacity
Upgrade F.......2TB....2TB....2TB....2TB....2TB....2TB..........8TB......Dual Redundancy, Increase in capacity

[Jedi Knight]

Note: XRAID2 with Dual Redundacy requires minimun of 4 hard disks with free space for Vertical Expansion.

Take a look at the ** area.

Option 1
Note.............Bay1...Bay2...Bay3...Bay4...Bay5...Bay6.....Capacity.....Notes
Initial Setup....1TB....1TB....1TB....1TB........................... 2TB......Put all 4 drives in before initial Pro powerup/setup, power on, then set to DR, XR-2
Upgrade A.......1TB....1TB....1TB....1TB....1TB..................3TB......Dual Redundancy
Upgrade B.......1TB....1TB....1TB....1TB....1TB....1TB..........4TB......Dual Redundancy
Upgrade C.......2TB....1TB....1TB....1TB....1TB....1TB..........4TB......Dual Redundancy, No increase in capacity
Upgrade D.......2TB....2TB....1TB....1TB....1TB....1TB..........4TB......Dual Redundancy, No increase in capacity
Upgrade E.......2TB....2TB....2TB....1TB....1TB....1TB..........4TB......Dual Redundancy, No increase in capacity
Upgrade F.......2TB....2TB....2TB....2TB....1TB....1TB..........6TB**......Dual Redundancy+start to increase capacity
Upgrade G.......2TB....2TB....2TB....2TB....2TB....1TB..........7TB**......Dual Redundancy
Upgrade H.......2TB....2TB....2TB....2TB....2TB....2TB..........8TB**......Dual Redundancy



Option 2
Note.............Bay1...Bay2...Bay3...Bay4...Bay5...Bay6.....Capacity.....Notes
Initial Setup....1TB....1TB....1TB....1TB........................... 2TB......Put all 4 drives in before initial Pro powerup/setup, power on, then set to DR, XR-2
Upgrade A.......1TB....1TB....1TB....1TB....2TB..................3TB......Dual Redundancy, Increase in capacity
Upgrade B.......1TB....1TB....1TB....1TB....2TB....2TB..........4TB......Dual Redundancy, Increase in capacity
Upgrade C.......2TB....1TB....1TB....1TB....2TB....2TB..........4TB**......Dual Redundancy, no Increase in capacity
Upgrade D.......2TB....2TB....1TB....1TB....2TB....2TB..........6TB**......Dual Redundancy, Increase in capacity
Upgrade E.......2TB....2TB....2TB....1TB....2TB....2TB..........7TB......Dual Redundancy, Increase in capacity
Upgrade F.......2TB....2TB....2TB....2TB....2TB....2TB..........8TB......Dual Redundancy, Increase in capacity

[mdgm]

Note: XRAID2 with Dual Redundacy requires minimun of 4 hard disks with free space for Vertical Expansion.

For those that don't know the difference between horizontal and vertical expansion:

Horizontal expansion: empty drive bay, add disk, if additional redundant space available get volume expansion
Vertical expansion: replace disk with higher capacity disk, in case of dual-redundancy if free space available on 4 hard disks get volume expansion.

[thomasvs]

Can someone explain the rather cryptic note:
"Note: XRAID2 with Dual Redundacy requires minimun of 4 hard disks with free space for Vertical Expansion."

It probably explains why in the second post, Option 2, Upgrade C (3 1TB, 3 2TB) doesn't add any free space, and Upgrade D(2 1TB, 4 2TB) adds 2 TB of space.

I'm in this exact situation now, and I don't understand why X-RAID isn't capable of using the full capacity you would get if you did this array from scratch in Upgrade C (dual redundancy so 2 of the biggest drive are out for capacity calculation, leaving 3 x 1 + 2 = 5 TB full capacity)

[mdgm]

Vertical expansion is explained in my post above.

X-RAID2 dual-redundancy uses RAID-6 layers. RAID-6 layers require a minimum of four disks. So Upgrade C gives 6x1TB + 3x1TB which isn't enough for a second RAID-6 layer as the second layer only has 3 disks. All the data must be stored so that if any two disks fail data remains intact.