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From Nate McCall <>
Subject Re: commitlog_total_space_in_mb tuning
Date Mon, 10 Jul 2017 01:52:03 GMT
> We're running with 128G memory and 30G heap size. Maybe it's good idea
> to increase the commitlog_total_space. On the other hand, even with  8G
> commitlog_total_space, replaying CL after restart takes more than 5
> minutes.
> In our case, the actual problem is it's causing lots of read repair
> timeouts as the repair mutations are dropped. Which causes Cassandra JVM
> hang or sometimes crash.

Do you have a mix of a small number of really heavily written to tables and
a larger number of tables with fewer writes?

One thing I've had success with when waitingOnSegmentAllocation spiked is
setting memtable_flush_period_in_ms on the less busy tables (obviously not
all the same so you don't flush storm). This seems to keep the
block-and-tackle CL rotation cleaner with fewer tables to flush.

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