I think it would be very useful to get to the bottom of this but without further details (like the asked for GC logs) I'm not sure what to do/suggest.
It's clear that a single CF with a 64 MB memtable flush threshold and without key cache and row cache and some bulk insertion, should not be causing the problems you are seeing, in general. Especially not with a > 5 gb heap size. I think it is highly likely that there is some little detail/mistake going on here rather than a fundamental issue. But regardless, it would be nice to discover what. -- / Peter Schuller
