Monitoring and adjusting caching
In the event of high memory consumption, consider tuning data caches.
Make changes to cache options in small, incremental adjustments, then monitor the effects of each change using nodetool info.
The cassandra.yaml file provides options for adjusting row cache and key cache settings:
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Cache size in bytes
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Capacity in bytes
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Number of hits
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Number of requests
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Recent hit rate
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Duration in seconds after which the database saves the key cache.
For example, on start-up, the information from nodetool info might look something like this:
ID : 387d15ba-7103-491b-9327-1a691dbb504a Gossip active : true Thrift active : true Native Transport active: true Load : 65.87 KB Generation No : 1400189757 Uptime (seconds) : 148760 Heap Memory (MB) : 392.82 / 1996.81 datacenter : datacenter1 Rack : rack1 Exceptions : 0 Key Cache : entries 10, size 728 (bytes), capacity 103809024 (bytes), 93 hits, 102 requests, 0.912 recent hit rate, 14400 save period in seconds Row Cache : entries 0, size 0 (bytes), capacity 0 (bytes), 0 hits, 0 requests, NaN recent hit rate, 0 save period in seconds Counter Cache : entries 0, size 0 (bytes), capacity 51380224 (bytes), 0 hits, 0 requests, NaN recent hit rate, 7200 save period in seconds Token : -9223372036854775808
