On 6/15/2012 12:49 PM, Otis Gospodnetic wrote: > Hi, > > How exactly does SolrCloud handle split brain situations? > > Imagine a cluster of 10 nodes. > Imagine 3 of them being connected to the network by some switch and imagine > the out port of this switch dies. > When that happens, these 3 nodes will be disconnected from the other 7 nodes > and we'll have 2 clusters, one with 3 nodes and one with 7 nodes and we'll > have a split brain situation. > Imagine we had 3 ZK nodes in the original 10-node cluster, 2 of which are > connected to the dead switch and are thus aware only of the 3 node cluster > now, and 1 ZK instance which is on a different switch and is thus aware only > of the 7 node cluster. > > At this point how exactly does ZK make SolrCloud immune to split brain?
A quorum of N/2+1 nodes is required to operate (that's also the reason you need at least 3 to begin with)
