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From Dmitry Olshansky <>
Subject Re: Cassandra as storage for cache data
Date Mon, 01 Jul 2013 11:54:00 GMT

thanks to all for your answers and comments.

What we've done:
- increased Java heap memory up to 6 Gb
- changed replication factor to 1
- set durable_writes to false
- set memtable_total_space_in_mb to 5000
- set commitlog_total_space_in_mb to 6000

If I understand correctly the last parameter has no matter since we set 
durable_writes to false.

Now the overall performance is much better but still not outstanding. We 
continue observing quite frequent compactions on every node.

According to OpsCenter's graphs Java Heap never grows above 3.5 Gb. So 
there is enough memory to keep memtables. Why they still get flushed to 
disk triggering compactions?

Best regards,
Dmitry Olshansky

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