Galera 3.19 comes with improvements to better handle the situation where the entire cluster needs to be restarted. In previous blog post, we already discussed one such feature: Safe-to-Bootstrap.
In this post, we will discuss gcache recovery, which allows for the cluster to be restarted quickly after it was shut down, thus reducing the overall duration of planned or unplanned downtime.
The Gcache and Whole-Cluster Restarts
In previous versions of Galera, When a node starts up, its Gcache is wiped clean. This means that this node can not serve as an IST donor to other nodes that are also starting up at the same time. This is especially important when the entire cluster is being restarted. When the second node starts, it hopes to quickly rejoin the cluster via IST from the first node: