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https://issues.apache.org/jira/browse/CASSANDRA-9474?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15003120#comment-15003120
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Paulo Motta commented on CASSANDRA-9474:
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Thanks for the patch [~molsson]! In fact, the only reason I see for
PropertyFileSnitch to be reloadable is to add new nodes, but this is not
necessary on GossipingPropertyFileSnitch as you mentioned.
The patch looks good. We're towards the end of 2.1 development so we're
avoiding adding changes at this stage, could you update/rebase your patch to
2.2 and 3.0? A few remarks:
* Register the {{ReconnectableSnitchHelper}} only if prefer_local=true
** I thought we could do the same with broadcasting the INTERNAL_IP, but better
to always broadcast in case this is needed somewhere else.
* As you noted, CASSANDRA-10242 already added the check to the rack, so if you
could add the dc check on the top of that it would be nice. Since the
{{cassandra.ignore_rack}} was introduced and documented, then I think we should
add an additional property {{cassandra.ignore_dc}} to be consistent.
** Please add a note to {{NEWS.txt}} (on 2.2.4) similar to
[this|https://github.com/apache/cassandra/blob/29ff1f2ac2a3da16f75ce87555df8f6014c8303e/NEWS.txt#L21]
of CASSANDRA-10242.
If you have access to a cassandra-dtest environment, it would be nice if you
could create a variant of [this
dtest|https://github.com/carlyeks/cassandra-dtest/blob/47ceb7995c6a4f9599c8a257f995c75ec518b241/replication_test.py#L460]
to check if the startup fails when the DC is changed. Otherwise I can create
it before accepting the patch.
> DC/Rack property changed on live system
> ---------------------------------------
>
> Key: CASSANDRA-9474
> URL: https://issues.apache.org/jira/browse/CASSANDRA-9474
> Project: Cassandra
> Issue Type: Bug
> Environment: Cassandra 2.1.5
> Reporter: Marcus Olsson
> Assignee: Marcus Olsson
> Fix For: 2.1.x
>
> Attachments: cassandra-2.1-9474.patch,
> cassandra-2.1-dc_rack_healthcheck.patch
>
>
> When using GossipingPropertyFileSnitch it is possible to change the data
> center and rack of a live node by changing the cassandra-rackdc.properties
> file. Should this really be possible? In the documentation at
> http://docs.datastax.com/en/cassandra/2.1/cassandra/initialize/initializeMultipleDS.html
> it's stated that you should ??Choose the name carefully; renaming a data
> center is not possible??, but with this functionality it doesn't seem
> impossible(maybe a bit hard with changing replication etc.).
> This functionality was introduced by CASSANDRA-5897 so I'm guessing there is
> some use case for this?
> Personally I would want the DC/rack settings to be as restricted as the
> cluster name, otherwise if a node could just join another data center without
> removing it's local information couldn't it mess up the token ranges? And
> suddenly the old data center/rack would loose 1 replica of all the data that
> the node contains.
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