--replicas
flag to
assign the same group to multiple nodes. The number passed to the --replicas
flag causes that Zero node to assign the same group to the specified number of
nodes. These nodes will then form a Raft group (or quorum), and every write will
be consistently replicated to the quorum.
To achieve consensus, it’s important that the size of quorum be an odd number.
Therefore, we recommend setting --replicas
to 1, 3 or 5 (not 2 or 4). This
allows 0, 1, or 2 nodes serving the same group to be down, respectively, without
affecting the overall health of that group.