It depends on cassandra version. As far as I know in 1.2 coordinator logs request before it updates replicas. If it fails it will replay log on startup.
In 1.1 you may have inconsistant state, because only part of your request is propagated to replicas.

Thank you,
  Andrey


On Tue, Jun 25, 2013 at 5:11 PM, Jiaan Zeng <jiaan@bloomreach.com> wrote:
Hi there,

I am writing data to Cassandra by thrift client (not hector) and
wonder what happen if the coordinator node fails. The same question
applies for bulk loader which uses gossip protocol instead of thrift
protocol. In my understanding, the HintedHandoff only takes care of
the replica node fails.

Thanks.

--
Regards,
Jiaan