2011/3/6 aaron morton <aaron@thelastpickle.com>
Your node is under memory pressure, after the GC there is still 5.7GB in use. In fact it looks like memory usage went up during the GC process.

Can you reduce the memtable size, caches or the number of CF's or increase the JVM size? Also is this happening under heavy load ?

Yes I do bulk load to cluster

I reduce memtable to 64MB sutuation became better, but it is all the same very rare GC more than 15 Sec happens. Can reduce   flush_largest_memtables_at helps? O may be some GC options?