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From Raj N <>
Subject Cassandra 2 DC deployment
Date Tue, 12 Apr 2011 15:12:42 GMT
Hi experts,
     We are planning to deploy Cassandra in 2 datacenters. Let assume there
are 3 nodes, RF=3, 2 nodes in 1 DC and 1 node in 2nd DC. Under normal
operations, we would read and write at QUORUM. What we want to do though is
if we lose a datacenter which has 2 nodes, DC1 in this case, we want to
downgrade our consistency to ONE. Basically I am saying that whenever there
is a partition, then prefer availability over consistency. In order to do
this we plan to catch UnavailableException and take corrective action. So
try QUORUM under normal circumstances, if unavailable try ONE. My questions
Do you guys see any flaws with this approach?
What happens when DC1 comes back up and we start reading/writing at QUORUM
again? Will we read stale data in this case?


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