Have RAID5, 5TB populated out of 10 available: any hope of increasing to RAID6 without reloading?

[PeteCress]

Somehow I messed up in my RAID level specification.

Now, after two days of loading, my new RN316 with 4-4tb drives has 5 tb of data on it but the RAID level is only 5 and I wanted 6.

Projected capacity at 6 is 7.something tb and only 5 tb is loaded - so it would seem like there might be a glimmer of hope....

I have no probem with buying a couple more 4-tb drives because that's where I am headed anyhow.

The Question:

Is there a way for me to change from RAID5 to RAID6 without having to reload the array?

[PeteCress]

I cannot find any way to edit my OP, so here goes....

I think I answered my own question and the answer is "No, a RAID5 array cannot be upgraded to RAID6 without wiping the data and then reloading after the upgrade.".

But that begs another question: Do I want RAID6 or X-RAID2?  

The desired bottom line is that the box can have two (2) drives fail and still not lose any data.

??

[Sandshark]

If you are going to be wiping things out and stating over, you may want to consider moving to OS6 on your Ultra6.  It gets rid of a lot of the volume limitations, allows you to move between XRAID and FlexRAID (as long as there is only one data volume), and is based on a current Debian distro.

[jak0lantash]

Don't be confused about the "2" in X-RAID2, it's just the name of the feature as shown on your device. It was called X-RAID on RAIDiator 4.1, then X-RAID2 on RAIDiator 4.2, and X-RAID again on ReadyNAS OS6.

To use RAID6 on your Ultra6, you need to use Flex-RAID (For OS6: disable X-RAID after initial setup, recreate the volume as desired. For RAIDiator 4.2: use RAIDar during initial setup.).

[PeteCress]

My bad: I muddied the waters device-wise.

I do have an Ultra-6, but the question is about my new RN316.

The plan long-term is to put OS-6 on the ultra, but here-and-now I want to get the 316 up and running with 2-drive redundancy.

Can anybody:

• Confirm that I really do have to wipe the current RAID5 array before making the 316 2-drive-redundant?
• Give the exact, precise, letter-for-letter name of what I am looking for 2-drive-redundancy-wise? .... So far, it is sounding like "RAID6".

[jak0lantash]

Using the GUI, you won't be able to modify your RAID5 array into a RAID6 array.

From the back-end, there is a solution:

- disable X-RAID.

- insert a 5th drive.

- use mdadm to reshape your RAID array from 4-disks RAID5 to 5-disks RAID6.

But I wouldn't advise doing that unless you're confident with SSH and mdadm.

So I do advise you to wipe the array and recreate as RAID6 for dual redundancy.

[xiao123]

It's no need to work in the backend. You can follow below steps via admin UI:
1. Disable X-RAID
2. Insert the 5th drive
(the drive capacity should be 4TB or larger size)
3. Select the 5th drive, and click the button of "Add Parity", then raid5 change to be raid6 mode successfully.

[jak0lantash]

Thanks for correcting.

[PeteCress]

Once we have RAID6, is there any way to go back to RAID5 without having to reload the array? (i.e. maybe in the future one would decide that the benefit of more space outweighed the benefit of the extra redunant disk).

[mdgm-ntgr]

No

[PeteCress]

Did the deed: inserted an empty 4tb drive, clicked "Add Parity" and it's been cooking for a couple days now.   Current projected completion is in 137 hours (six more days !).

Now I notice that the X-RAID button has gone grey and clicking it throws this "X-RAID Mode" dialog: 

The Question:

Once the RAID5-to-RAID6 process is completed, I want to click that button and answer "Yes", right?

Otherwise I would not be able to add the sixth-and-final 4tb drive...

(??)

[Sandshark]

You don't have to if you don't mind expanding it manually (click "Expand" instead of "Add parity").  If you have the possibility of incrementally bumping up drives to a larger size later, XRAID will definately make that easier.

[jak0lantash]

Afaik, Flex-RAID horizontal expansion is not linear like X-RAID, it requires adding a new vdev and concatenating both in the BTRFS volume. So if you have a volume made of a single 5 HDDs RAID array, in order to horizontally expand in Flex-RAID mode, you need to add 5 disks.

I don't understand why the question though, turning on X-RAID is what you want to do.

[PeteCress]

> I don't understand why the question though, turning on X-RAID is what you want to do.

I don't understand the question either - and I wrote it..... -)

But you have answered it:  bottom line, once this thing gets up to RAID6, I am where I am not yet where Iwant to be because I am still under Flex-RAID and I need to click the X-RAID button to get X-RAID at dual redunancy.

Once that is done, I pop in the sixth-and-last drive and the box adds it to the array.

??