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From Robert Coli <>
Subject Re: SchemaDisagreementError when launching a new Cassandra (1.2.2) cluster ?
Date Mon, 09 Sep 2013 16:51:14 GMT
On Mon, Sep 9, 2013 at 8:07 AM, Alex Heneveld <> wrote:

> The problem occurs in about 1 in 4 launches when I start a 2-node cluster,
> where the two machines are configured identically with both nodes as the
> seeds (apart from the listen_address being different). On the problematic
> launches, describing schema versions immediately after start shows that the
> two nodes have different schemas (reported at both nodes) and any attempt
> to work with the nodes returns the SDE.  This is before I attempt to do
> anything to the cluster.  After ~60s the nodes reconcile their differences,
> report a single schema used at both nodes, and I can use the cluster
> without problems.

How are you defining the schema?

> I have a workaround, which is to use just one node to seed this initial
> set.  When the set of seeds is cardinality 1, the problem does not occur.
>  However the advice is to use 2 seeds and have them be the same across the
> cluster -- so I'd like to get to the bottom of this!

Seed nodes "cannot" bootstrap [1], so if you have RF=N and all nodes as
seeds, I'm not surprised that you are experiencing weird behavior. A node
booting with itself as a seed typically just starts up as a cluster of one.

> I am running Cassandra 1.2.2 running in Amazon, using Brooklyn (
> to start and manage it.  I can share test cases,
> cassandra.yaml, logs, etc -- but am starting with the above summary in case
> anyone can point me in the right direction from that.

Cassandra 1.2.2 has significant bugs. You should launch with 1.2.9.

1.2.9 also has some bootstrap vs. seed fixes which might help your case.


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