MySQL Cluster 6.3.28b and 7.0.9b contain optmizations which can greatly reduce the time taken for data nodes to restart – this includes restarting a single node, performing a rolling restart or a full system restart.

The benefits you see will depend on many factors including including the size of your database and the frequency, size and complexity of your transactions. As an experiment, I re-ran some data node restart timings from an earlier post (http://www.clusterdb.com/mysql-cluster/mysql-cluster-data-node-restart-times/)

The headline figure from my results is that for a 6 Gbyte database, with modest traffic I saw a 2.2x improvement. This is using very simple transactions and so you may get a much better improvement – 70x is

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Restarts are required for certain, infrequent maintenance activities. Note that there is no loss of service while a single node restarts.

When a data node restarts, it first attempts to load the data into memory from the local log files and then it will catch up with any subsequent changes by retrieveing them from the surviving node(s) in its node group.

 Based on this, you would expect the time taken to restart a data node to be influenced by:

The amount of data that was stored on the data node before the restart

Rate of updates being made to the data during the restart

Network performance (assuming the data is being updated during recovery)

The times will also be influenced bycertain configuration parameters, performance of the host machine and whether the multi-threaded data node (ndbmtd) is being used.

To

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