State Snapshot Transfer (SST) at a glance
PXC uses a protocol called State Snapshot Transfer to provision a node joining an existing cluster with all the data it needs to synchronize. This is analogous to cloning a slave in asynchronous replication: you take a full backup of one node and copy it to the new one, while tracking the replication position of the backup.
PXC automates this process using scriptable SST methods. The most common of these methods is the xtrabackup-v2 method which is the default in PXC 5.6. Xtrabackup generally is more favored over other SST methods because it is non-blocking on the Donor node (the node contributing the backup).
The basic flow of this method is:
- The Joiner:
- joins the cluster …