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cassandradatastaxdatastax-enterprise

Cassandra : impact of high compaction/streaming throughput values?


The defaults throughput are as follow (cassandra.yaml) :

compaction_throughput_mb_per_sec: 16
stream_throughput_outbound_megabits_per_sec: 200
inter_dc_stream_throughput_outbound_megabits_per_sec: 200

To speed up things like compaction, I have set those values :

$ nodetool getcompactionthroughput
Current compaction throughput: 10000 MB/s

$ nodetool getstreamthroughput
Current stream throughput: 10000 Mb/s

$ nodetool getinterdcstreamthroughput
Current inter-datacenter stream throughput: 10000 Mb/s

Cassandra data directories are backed by both SSD and HDD, depending of the keyspace.

Are there any impact (like read or write timeout) of applying such very high values ?

Thank you


Solution

  • Only impact I can see with high compaction throughput is that your traffic (read/writes) from the application may get impacted. As SSDs have finite IOPS capacity so giving most of it to compaction will impact your traffic at the time compaction is going on.