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From Rob Coli <rc...@palominodb.com>
Subject Re: Rename cluster
Date Thu, 29 Nov 2012 21:44:38 GMT
On Thu, Nov 29, 2012 at 11:56 AM, Wei Zhu <wz1975@yahoo.com> wrote:
> I am trying to rename a cluster by following the instruction on Wiki:
> [...]
> I have to remove the data directory in order to change the cluster name.
> Luckily it's my testing box, so no harm. Just wondering what has been
> changed not to allow the modification through cli? What is the way of
> changing the cluster name without wiping out all the data now?

The instructions on the wiki are wrong, because clients are now not
able to not able to update the system keyspace. The below ticket is an
expansion of the previous behavior, which must mean the behavior in
question dates to 0.8 or early 1.0.

https://issues.apache.org/jira/browse/CASSANDRA-3759

You don't need to remove the data directory to change the cluster
name, you only need to remove the contents of the system keyspace's
LocationInfo columnfamily, which is where Cluster Name is stored.

Full, safe, offline process to rename a cluster :
1) put new cluster name in conf files
2) stop cluster (including draining and removing commitlog if you are
in a version below 1.1.6 and cannot rely on drain to prevent log
replay)
3) move LocationInfo files out of system keyspace of all nodes
4) start cluster

I do not believe there is currently any online way to do the above
operation. The check which prevents you from writing to the system
keyspace is a keyspace level check.

=Rob

-- 
=Robert Coli
AIM&GTALK - rcoli@palominodb.com
YAHOO - rcoli.palominob
SKYPE - rcoli_palominodb

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