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From Peter Schuller <>
Subject Re: Does Cassandra fit my requirements?
Date Sat, 16 Oct 2010 12:37:41 GMT
> 2.  What we really want for small users is just a replicated data store with
> some caching.  Each of our application instances would have all the data
> available to it.  If one application instance goes down, the other nodes
> should continue to function just fine.

Sounds reasonable, but make sure your application logic is okay to
handle concurrent requests to multiple nodes for the same data. I.e.,
that there is no problem associated with your application not having
the only authoritative view of the data in-memory.

> So, with number 2, I've run into a situation that I don't think is going to
> work for me, but hopefully I'm just missing something.  To test 2., I
> installed a 2 node cluster.  On node A, I ran some code to populate one of
> the nodes.  On both A and B, I can get data.  Now, I shutdown node A and
> request data from Node B, I get a timed out exception from hector.  If I
> leave A running, but shutdown B, I get an IllegalStateException: replication
> factor (2) exceeds number of endpoints (1).  I have set my
> replication_factor to 2.
> Can I do what I want with Cassandra?  I appreciate any advice!  And I
> apologize in advance if I've missed something obvious, I have all of about
> 1.5 days experience and I'm trying to learn fast ;-)

Does both A and B agree about the ring state (i.e., they both know
about both nodes) prior to you shutting one of them down?

/ Peter Schuller

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