Hi all, we are seeing quite high GC pressure (in old space by CMS GC Algorithm) on a node with 4TB of data. It runs C* 1.2.18 with 12G of heap memory (2G for new space). The node runs fine for couple of days when the GC activity starts to raise and reaches about 15% of the C* activity which causes dropped messages and other problems.
Taking a look at heap dump, there is about 8G used by SSTableReader classes in org.apache.cassandra.io.compress.CompressedRandomAccessReader. Is this something expected and we have just reached the limit of how many data a single Cassandra instance can handle or it is possible to tune it better? Regards Jiri Horky
