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From Donald Smith <Donald.Sm...@audiencescience.com>
Subject RE: adding more nodes into the cluster
Date Fri, 01 Aug 2014 16:27:28 GMT
According to datastax’s documentation at http://www.datastax.com/documentation/cassandra/2.0/cassandra/operations/ops_add_dc_to_cluster_t.html
   “By default, this setting [auto_bootstrap] is true and not listed in the cassandra.yaml
file.”

But http://wiki.apache.org/cassandra/StorageConfiguration  says:
   “Default is: 'false', so that new clusters don't bootstrap immediately. You should turn
this on when you start adding new nodes to a cluster that already has data on it.”

So which is correct?

Also, the two pages disagree on the instructions on how to add new nodes to an existing cluster.
 The first page says to set auto_boostrap to ‘false’ when adding a new data center to
a cluster. “Setting this parameter to false prevents the new nodes from attempting to get
all the data from the other nodes in the data center. When you run nodetool rebuild<http://www.datastax.com/documentation/cassandra/2.0/cassandra/tools/toolsRebuild.html>
in the last step, each node is properly mapped.”

The second page suggests setting auto_boostrap to ‘true’ when you add new nodes to an
existing cluster: “You should turn this on when you start adding new nodes to a cluster
that already has data on it.”  Perhaps that applies only to new nodes to an existing data
center (not a new data center to an existing cluster).

So, I’m not clear what I should do.   I want to add a data center to an existing cluster.
  If I set auto_bootstrap to true in the new nodes of the new cluster, will it stream data
from the other data centers?  Perhaps it will stream only NEW rows.   Perhaps the purpose
of doing “nodetool rebuild” is to force streaming OLD data (like a repair).  It’s not
clear. Maybe auto_bootstrap=true is equivalent to (auto_boostrap=false plus “nodetool rebuild”).

Thoughts?

Don
Donald A. Smith | Senior Software Engineer
P: 425.201.3900 x 3866
C: (206) 819-5965
F: (646) 443-2333
donalds@AudienceScience.com<mailto:donalds@AudienceScience.com>

[AudienceScience]


From: Robert Coli [mailto:rcoli@eventbrite.com]
Sent: Wednesday, July 16, 2014 12:31 PM
To: user@cassandra.apache.org
Subject: Re: adding more nodes into the cluster

On Wed, Jul 16, 2014 at 12:28 PM, Robert Coli <rcoli@eventbrite.com<mailto:rcoli@eventbrite.com>>
wrote:
It applies whenever one is bootstrapping a node. One is bootstrapping a node whenever one
starts a node with auto_bootstrap set to "true" (the default) and with either one-or-more
tokens in initial_token or num_tokens set.

Ugh sorry :

1) starting a node
2) with auto_bootstrap:true (default)
3) initial_token or num_tokens populated
4) node has never successfully bootstrapped before, and has not therefore written the information
of its successful bootstrap to the system keyspace

If the node has bootstrapped before, it will not do so again unless replace_address is used.

=Rob


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