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From Thomas Whiteway <>
Subject RE: Cassandra seems to replace existing node without specifying replace_address
Date Thu, 28 May 2015 09:00:32 GMT
Sorry, I should have been clearer.  In this case we’ve decommissioned the node and deleted
the data, commitlog, and saved caches directories so we’re not hitting CASSANDRA-8801. 
We also hit the “A node with address <address> already exists, cancelling join”
error when performing the same steps on 2.1.0, just not in 2.1.4.


From: Robert Coli []
Sent: 27 May 2015 20:41
Subject: Re: Cassandra seems to replace existing node without specifying replace_address

On Wed, May 27, 2015 at 5:48 AM, Thomas Whiteway <<>>
I’ve been investigating using replace_address to replace a node that hasn’t left the cluster
cleanly and after upgrading from 2.1.0 to 2.1.4 it seems that adding a new node will automatically
replace an existing node with the same IP address even if replace_address isn’t used.  Does
anyone know whether this is an expected change (as far as I can tell it doesn’t seem to

This is a longstanding known issue ("Cassandra has had this behavior since the inception of
decom"), with a fix recently (May 19, 2015) merged to trunk.

The basic problem is that the node does not forget its own cluster membership information,
and so joins the cluster using its stored tokens. In my opinion, "decommission" should wipe
all stored node state, but 8801 creates a workaround that addresses this, the worst case.


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