Migrate RAID1 to SnapRaid

My OMV currently runs on Raid1 with 2 data drives, 2TB each.

I think it would make sense for me to move to SnapRAID.

If i buy a third 2 TB drive for parity, can i migrate to SnapRAID without reformatting the data drives?

How to best do this?

I guess this should work if i copy all data content on the new drive and then use one of the old RAID drives as the parity drive. The third one i can just attach as a new expansion to the existing SNAP Array.

?

Yeah well maybe i will go for a 4TB drive. But anything bigger i dont really need just right now and will not be any cheaper per MB.

Although this would mean the 4TB drive has to be the parity drive. As per Snapraid formula the parity drive has to have the size of the biggest data drive at least. Correct?

Of course i might need some more space some day. But i try to keep the amount of data reasonable and throw away what i do not need. I do the same in real life and it is really helpfull A lot of people collect a lot of stuff they just dont need.

Right now i am at 95% with my 2 TB. But moving to Snapraid as described above I will gain 2 TB and with a new 4 TB drive even more. I am not sure how much in that case as i dont really know a lot about Snapraid configuration yet.

The plan so far is:

1. get a new 4tb drive as parity drive

2. build new Snap array with 1 of the 2 old Raid 1 drives as data and the new 4tb as parity. So i will still have all data on the second Raid1 drive.

3. copy data from second Raid1 disk to the now existing Snap array

4. Integrate second Raid1 disk into Snap array.

5. done

Now i read this post which states that the above does not work as Snap asks for at least 2 content disks from the beginning on: SnapRaid + UnionFS NAS with 2 disks

How can i achieve a migration then?

This is solved for me. I will first migrate the data then build a UnionFS with 2 drives and when everything runs include the third drive as parity