Xraid2 dual redundant vs FlexRaid 6?

You are correct, once you have gone to xraid with dual redundancy.
The advantage of xraid with OS4 (which I assume you are using) is that you can start with single redundancy when your volume is small and change up to dual redundancy later. With flexraid you would have to start from scratch in order to move from raid 5 to raid 6.

Unfortunately this advantage has been removed from OS6 where one cannot easily move from single to dual redundancy.

I had another thread asking this question but deleted it and merge it here since they're related.

I have 2x 1Tb and 4x 2Tb configured it to a Flex Raid 6 and it's only seeing 4Tb. I thought Flex Raid 6 is supposed to give me 6 TB with 2 drives redundant?

So I flipped out and reset the NAS and configured FlexRaid dual redundant and I'm still seeing 47 GB (1%) of 3683 GB used which tells me I still only have 4Tb. Do I have to wait until all the resync is done? There are no data on any drives at the moment and all drives were in place after the factory reset.

All 6 drives is showing 927 GB allocated only while 4 of the drives are actually 2Tb. So what does it mean when it says "allocated"? If it means usable storage then I should have 6Tb once complete?

There's no downside to using xraid2 dual redundancy in OS4, and generally I recommend xraid2 unless there's a reason not to.

dannieboiz wrote:

I had another thread asking this question but deleted it and merge it here since they're related. I have 2x 1Tb and 4x 2Tb configured it to a Flex Raid 6 and it's only seeing 4Tb. I thought Flex Raid 6 is supposed to give me 6 TB with 2 drives redundant? So I flipped out and reset the NAS and configured FlexRaid dual redundant and I'm still seeing 47 GB (1%) of 3683 GB used which tells me I still only have 4Tb. Do I have to wait until all the resync is done? There are no data on any drives at the moment and all drives were in place after the factory reset. All 6 drives is showing 927 GB allocated only while 4 of the drives are actually 2Tb. So what does it mean when it says "allocated"? If it means usable storage then I should have 6Tb once complete?

Flipping out often leads to bad results with a NAS. :wink:

There are two phases to building a volume with mixed disks. You can visualize it as building a layer cake.

The first phase is to build a layer across all the drives, using the size of the smallest. In your case that would be 6x1TB RAID-6. That would give you 4 TB of storage.

The second phase is "vertical expansion" - adding a second layer across the larger size drives using the remaining space. That would be a 4x1TB layer in your case, and should have added the additional 2nd 2 TB.

Based on your info, it appears that the vertical expansion step simply didn't start. In particular, that is why you are seeing 927GB allocated on all drives.

My advice is to do another factory default with xraid2. If the second phase doesn't seem to start, then simply reboot the NAS. Sometimes 2 or three reboots seem to be needed.

If that doesn't work, contact support at support.netgear.com and followup on this thread.

it's still resyncing at the moment. Got about 7 hours to go, does the vertical expansion happen along side with resyncing? Should I wait for resync to complete then worry if I don't see the other 2Tb come in?

dannieboiz wrote:
it's still resyncing at the moment. Got about 7 hours to go, does the vertical expansion happen along side with resyncing? Should I wait for resync to complete then worry if I don't see the other 2Tb come in?

They are separate phases (sequential, not parallel).

Wait for it...

That's good to know. :) Thought by having all 6 disk in and then do the factory reset would show the full usable space.

So bottom line is whether xraid 2 dual redundant or FlexRaid 6 it doesn't matter since I have all 6 disk in already.

No it doesn't matter, but the facility to use flexraid was I assume intended for scenarios where users wanted something that xraid does not offer, like multiple volumes, JBOD, raid0, raid10.
For your purposes the default mode, xraid , gives you what you need so there is no advantage in using flexraid.