[DRBD-user] three node backup setup without public/internal IP address

[Sven Duscha]

Hi,

I am trying to set up a three-way redundant DRBD. The way I understand
it, this is only possible as a primary/secondary-pair with an "external"
stacked-on-top backup.

resource r0 {
   disk {
        resync-rate 40M;
    }

    net {
        verify-alg sha1;
        protocol C;
    }

   on ibis-vstest-01 {
       device        /dev/drbd0;
        disk            /dev/sdb1;
        address        146.107.216.240:7789;
        meta-disk    internal;
    }
   
    on ibis-vstest-02 {
        device        /dev/drbd0;
        disk            /dev/sdb1;
        address        146.107.216.241:7789;
        meta-disk    internal;
    }
}

resource r0-U {
    net {
        protocol A;
    }

    stacked-on-top-of r0 {
        device        /dev/drbd10;
        address        146.107.216.242:7789;
    }

    on ibis-vstest-03 {
        device        /dev/drbd10;
        disk            /dev/sdb1;
        address        146.107.216.242:7789;
        meta-disk    internal;
    }
}

The problem is that my third node is within the same IP range as the
other two. Therefore is no dedicated second IP interface with an
external IP. I then get an error message about a doubly assigned IP address.

Is the a way to create a such setup within the same cluster? I read up a
bit on the Pacemaker section which proposes a three-way and four-way
method, though, also intended to be "external". Do I need the commercial
DRBD-Proxy for the Pacemaker-setup or is this optional?

Cheers,

Sven

-- 
Sven Duscha, M.Sc.
Systemadministrator
Institute of Bioinformatics and Systems Biology