Monitoring and adjusting caching
Use nodetool to make changes to cache options and then monitor the effects of each change.
- Cache size in bytes
- Capacity in bytes
- Number of hits
- Number of requests
- Recent hit rate
- Duration in seconds after which Cassandra saves the key cache.
For example, on start-up, the information from nodetool info might look something like this:
Token : (invoke with -T/--tokens to see all 256 tokens) ID : 387d15ba-7103-491b-9327-1a691dbb504a Gossip active : true Thrift active : true Native Transport active: true Load : 11.35 KB Generation No : 1384180190 Uptime (seconds) : 437 Heap Memory (MB) : 136.33 / 1996.81 Data Center : datacenter1 Rack : rack1 Exceptions : 0 Key Cache : size 360 (bytes), capacity 103809024 (bytes), 15 hits, 19 requests, 0.789 recent hit rate, 14400 save period in seconds Row Cache : size 0 (bytes), capacity 0 (bytes), 0 hits, 0 requests, NaN recent hit rate, 0 save period in seconds
In the event of high memory consumption, consider tuning data caches.
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