The rate_in_kb sets the per node rate of the local NodeSync service. It controls the maximum number of bytes per second used to validate data. There is a fundamental tradeoff between how fast NodeSync validates data and how many resources it consumes. The rate is a limit on the amount of resources used and a target that NodeSync tries to achieve by auto-tuning internals. The set rate might not be achieved in practice, because validation can complete at a slower rate on new or small cluster or the node might temporarily or permanently lack available resources.

There is no strong requirement to keep all nodes validating at the same rate. Some nodes will simply validate more data than others. When setting the rate, use the simplest method first by using the defaults.

When adjusting rates, use the NodeSync rate simulator to help determine the configuration settings by computing the rate necessary to validate all tables within their allowed deadlines.

Unfortunately, no perfect value exists because NodeSync also deals with many unknown or difficult to predict factors, such as:

All these factors can impact the overall NodeSync rate. Therefore build safety margins within the configured rate. The NodeSyncServiceRate simulator helps to set the rate.