Starting a cluster
On the first selected node, execute:
When the first node is up and running, execute the following command on the subsequent nodes:
It will now automatically retrieve the cluster map and connect to the rest of the nodes and form a cluster.
Safe-to-Bootstrap flag facilitates the decision and prevents unsafe choices by keeping track of the order in which nodes are being shut down. The node that was shut down last will be marked as "Safe-to-Bootstrap". All the other nodes will be marked as unsafe to bootstrap from. Looking at
# GALERA saved state version: 2.1 uuid: 8bcf4a34-aedb-14e5-bcc3-d3e36277729f seqno: 2575 safe_to_bootstrap: 0
In case of unclean shutdown or hard crash, all nodes will have safe_to_bootstrap: 0. Consult the InnoDB storage engine to determine which node has committed the last transaction in the cluster. The number after the
UUID string on the "Recovered position" line is the one to look for. Pick the node that has the highest number and edit its
grastate.dat to set
safe_to_bootstrap: 1, as shown in the example below:
# GALERA saved state version: 2.1 uuid: 8bcf4a34-aedb-14e5-bcc3-d3e36277729f seqno: -1 safe_to_bootstrap: 1
You can then perform the standard bootstrap command on the chosen node.