6 drive RAID 10 triple redundant instead of double

[Ben]

I’ve tried researching on my own, maybe I don’t know how to phrase it.

I’m wanting to build a RAID 10 with six 3Tb drives.

I’m looking to set up up a bit differently than what I can find on the net.

Instead of 2 redundant arrays of replication I’m going for 3.

                         RAID 0
          RAID 1                 RAID 1
        A1 B1 C1              A2 B2 C2
        A1 B1 C1              A2 B2 C2
        A1 B1 C1              A2 B2 C2

does this make sense?
Is this possible?

I’m sorry if this is in the wrong category.

Thanks,

[phillxnet (Philip Guyton)]

@Ben First off - welcome to the Rockstor community forum.

As btrfs’s raid works at the chunk level and it’s current implementation of raid1 is 2 way not n-way, you can’t define what you are after, assuming you are specifying a 3-way raid 1 (at the lower level): ie 3 copies of everything. Btrfs raid 1 only does 2 copies on 2 different devices and btrfs raid 10 is, as you indicate, a stripe over 2 or more raid1(2-way) mirrored drives(at the chunk level). So note that if you have 3 drives in btrfs raid1, one chunk may be on drive 1 and 2 while another chunk may be on drive 2 and 3 so chunk not drive level of raid.

@Spectre694 does a nice explanation of btrfs raid levels and capabilities in the following thread started by @Bayonet:

Specifying individual drives in each pair of each mirror for RAID10

Hello Rockstor community, After repeated dissatisfaction with Freenas and ZFS I have decided to give a BTRFS implementation a try, so far I am loving the responsiveness, ease of use and visual design of the UI in Rockstor. However, I have encountered something which concerns me with the way RAID10 is displayed. As you can see below, I have twelve drives, six of which are Seagate, six Western Digital. My theory behind this is that I am more likely to have two drives from the same manufacturer fa…

Hope that helps.

[Ben]

Helps a lot, Thanks!

[phillxnet (Philip Guyton)]

@Ben

Helps a lot, Thanks!

Cheers, let us know how you get on.

[Ben]

Is it possible to Raid-1 mirror on 3 drives (triple copy rather than double) of the same size using BTRFS?

or no matter what, RAID 1 is two copies only?

I love BTRFS for the bitrot protection, and am really looking for a triple copy of my information (really don’t want to risk losing anything)

[Spectre694]

Afraid not regardless of what you do BTRFS RAID 1 is a 2 way setup and it isn’t possible to do n-way. The only way to be able to survive a two disk failure with BTRFS is by using RAID 6. HOWEVER BTRFS’s RAID 5/6 has been found to have multiple severe bugs and cannot be recommended at the moment.