[Gluster-users] HA storage based on two nodes with one point of failure

Юрий Полторацкий y.poltoratskiy at gmail.com
Sat Jun 6 09:09:43 UTC 2015


I want to build a HA storage based on two servers. I want that if one goes
down, my storage will be available in RW mode.

If I will use replica 2, then split-brain can occur. To avoid this I would
use a quorum. As I understand correctly, I can use quorum on a client side,
on a server side, or on both. I want to add a dummy node without a brick
and make such config:

cluster.quorum-type: fixed
cluster.quorum-count: 1
cluster.server-quorum-type: server
cluster.server-quorum-ratio: 51%

I expect that client will have access in RW mode until one brick alive. On
the other side if server's quorum will not meet, then bricks will be RO.

Say, HOST1 with a brick BRICK1, HOST2 with a brick BRICK2, and HOST3
without a brick.

Once HOST1 lose a network connection, than on this node server quorum will
not meet and the brick BRICK1 will not be able for writing. But on HOST2
there is no problem with server quorum (HOST2 + HOST3 > 51%) and that's why
BRICK2 still accessible for writing. With client's quorum there is no
problem also - one brick is alive, so client can write on it.

I have made a lab using KVM on my desktop and it seems to be worked well
and as expected.

The main question is:
Can I use such a storage for production?

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