Galera is a quite useful piece of technology that allows us to build highly available database clusters. This is one of the reasons why we are hearing questions about it a lot during our MySQL consulting activities. If you wonder what it is, we have an introductory post that explains basic concepts and features of … Continued
Galera cluster, be it MariaDB Cluster, Percona XtraDB Cluster or Galera Cluster from Codership uses quorum calculations to make sure the data consistency is safe in case of a split-brain and that the majority of the nodes will continue to operate while nodes that are in the minority will stop executing changes. We have discussed … Continued
State transfer – SST or IST Let’s start by discussing what SST is and why we may want to avoid it if possible? We are not going into details regarding different types of state transfer methods in Galera. What should suffice to say is that there are two types – Incremental State Transfer (IST) and … Continued
As we have discussed in one of previous blogs, Galera uses a concept of quorum to determine if a given node is a part of the cluster and can proceed with handling the traffic or is it partitioned and should cease any operations. We have briefly touched how the quorum is calculated but we haven’t … Continued