[DRBD-user] DRBD (XFS) + Pacemaker + Corosync with 2 node and arbiter (virtual node) for no split brain: Stonith, Quorum needed?

aTTi attiuj at gmail.com
Wed Sep 17 22:23:29 CEST 2014

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


I want build a DRBD cluster, with no special primary/primary function, just
a normal primary and passive secondary node, as standard.
I will use XFS file system with Centos 7 with 2 NIC: eth0 for switch and
for internet, eth1 for direct cable (crosslink) to other server.
I will define 2 ring: ring 0: eth1 crosslink connection, ring1: eth0
connection. I hope normally never will use the ring1, just the ring0.

If I had just this 2 server with extra direct cable connection, 'split
brain' can happen (someone unplug all network cable from server 1 or from
server 2, for example).

I had more normal servers. I want to find the best solution, because I
don't want split brain and lost data. Also I don't want fix manually the
problems if I can find a solution what helps to (near) never happing split
brain, or other DRBD killer disaster...

My 3. server is near same hardware as server 1 and server 2 with a low
load. If needed I had server 4 too, with a little bigger load with same
hardware as server 3. I just want a safe, clear and simple DRBD solution.

My 4 ideas / plans:

1. use 3. server as virtual node (arbiter). Question: how? Using server 3
helps to avoid split brain situation?

2. use 3. server as backup server with iSCSI. (3. server also in same
gigabit switch) It's good idea? This solution can helps to avoid split

3. use the server 3 as stacked node with DRBD, I found this:


It helps to avoid split brain?

4. I add as normal passive node my 3. server for DRBD. It will be problem
for me because no direct connection for all 3 servers. I don't want this

What is the best? I don't want make any new solution. I just want a safe,
working DRBD. If 3. server not needed for that, I also not will use this,
just 2. But I think 3. server can help to be more safe this DRBD cluster.
Please help me to make that.

My plan:

using my server 3 for make safer my DRBD (in server 1 and server 2) and
make backup from that 2 server.
I just want real safe my data from server 1 + server 2.

For 2 node, Stonith recommended. I also want to use that.
I knows Stonith mechanism: it kills the server if needed. It's good... if
really needed.

I will use Pacemaker + Corosync to manage DRBD and services.

Quorum needed for me if I had +1 node for DRBD?

I used DRBD few times, but not I installed for servers.

Please describe me what is the best if I want use a normal active / passive
DRBD and I want to be the most safe solution, using server 3 for that.
I want the simplest / safest solution what works for most scenarios. I just
want to be a happy DRBD user.

Thank you,
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