> We've also seen similar problems > > https://issues.apache.org/jira/browse/CASSANDRA-1177
To be clear though; un-*flushed* data is very different from un-*compacted* data and the above seems to be about unflushed data? In my test case there was no problem at all flushing data. But my test was sustained write speeds up to 200 million rows and ~ 200 gb of space, and as the database grew larger the compaction goes goes up (as expected). For that particular workload it would probably have been beneficial to have a configurable concurrency on compactions as well (similar to how it is configurable for sstable flushing) because CPU was the bottleneck in the compaction process (i.e., after stopping inserts and letting compaction complete in the background, the compaction thread was CPU-bound and there was plenty of available I/O capacity). -- / Peter Schuller
