Ran Tavory <rantav <at> gmail.com> writes: > > I can't say exactly how much memory is the correct amount, but surely 1G is very little. By replicating 3 times your cluster now makes 3 times more work than it used to do, both on reads and on writes while the readers/writers continue hammering it the same pace. > > > So once you've upped your memory (try 4g, if not enough 8g etc) if this still doesn't help, you want to look at either adding capacity or slowing down your writes. > Which consistency level are you writing with? You can try ALL, this will slow down your writes just as much needed by the cluster to catch its breath (or so I hope, I never actually tried that...)
Thank you so much, Ran! I am running on ec2-smalls and they have only 1.7GB of memory in total so 1GB of heap space is probably the highest I can go until we move to larger VMs. But you bring up an EXCELLENT point -- changing the consistency level. Because we are trying to populate the database as quickly as possible for our prototyping work, we use consistency of ZERO(!) I am going to try changing it to ALL as you suggest and also possibly throttle the writes. Does this seem like a Cassandra bug or is it well known that Cassandra always needs more than 1GB of heap space? Thanks again for your help, Julie
