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 …