Tuning NodeSync validations

Configure validation rate to meet target deadlines.


The location of the system.log file is:
  • /var/log/cassandra/system.log
NodeSync tries to validate all tables within their respective deadlines, while respecting the configured rate limit. If a table is 10GB and has a deadline_target_sec=10 and the rate_in_kb is set to 1MB/sec, validation will not happen quickly enough. Configure the rate and deadlines realistically, take data sizes into account and adapt with data growth.
Important: For write-heavy workloads, where more than 20% of the operations are writes, you may notice CPU consumption overhead associated with NodeSync. If that's the case for you environment, DataStax recommends using nodetool repair instead of enabling NodeSync. See nodetool repair.
NodeSync records warnings to the system.log, if it detects any of the following conditions:
  • rate_in_kb is too low to validate all tables within their deadline, even under ideal circumstances.
  • rate_in_kb cannot be sustained by the node (too high for the node load/hardware).