[jira] [Commented] (CASSANDRA-10243) Warn or fail when changing cluster topology live

["Stefania (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-10243?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14996237#comment-14996237 ] 

Stefania commented on CASSANDRA-10243:
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Before I start work, can I confirm the fix version, 2.1, and the snitches: {{YamlFileNetworkTopologySnitch}}, {{PropertyFileSnitch}} and {{GossipingPropertyFileSnitch}}. Note that {{YamlFileNetworkTopologySnitch}} was deleted in 2.2.

For tracking rack and dc, everything should be already there, either in system peers, or the gossip application states, or the snitches themselves. If a snitch configuration update would result in a rack or dc change for a live node (a node that belongs to Gossiper.liveEndpoints) then we log a loud error message and do not update the snitch at all. Correct?

bq. I'm not even sure if we should allow a node to join the cluster when the rack changes on startup without an explicit operator intervention.

We can look at system peers and refuse to join unless the operator uses a specific system property, would this be OK?

> Warn or fail when changing cluster topology live
> ------------------------------------------------
>
>                 Key: CASSANDRA-10243
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-10243
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Tools
>            Reporter: Jonathan Ellis
>            Assignee: Stefania
>            Priority: Critical
>             Fix For: 2.1.x
>
>
> Moving a node from one rack to another in the snitch, while it is alive, is almost always the wrong thing to do.



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