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https://issues.apache.org/jira/browse/CASSANDRA-13327?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15951550#comment-15951550
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Paulo Motta commented on CASSANDRA-13327:
-----------------------------------------

Thanks for clarifying [~slebresne].

[~aweisberg] guess we can close this then? and maybe open another ticket with 
Sylvain's suggestion above to lift the max number of pending endpoints 
limitation for CAS if you're willing to take a shot at it?

> Pending endpoints size check for CAS doesn't play nicely with 
> writes-on-replacement
> -----------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-13327
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-13327
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Coordination
>            Reporter: Ariel Weisberg
>            Assignee: Ariel Weisberg
>
> Consider this ring:
> 127.0.0.1  MR UP     JOINING -7301836195843364181
> 127.0.0.2    MR UP     NORMAL -7263405479023135948
> 127.0.0.3    MR UP     NORMAL -7205759403792793599
> 127.0.0.4   MR DOWN     NORMAL -7148113328562451251
> where 127.0.0.1 was bootstrapping for cluster expansion. Note that, due to 
> the failure of 127.0.0.4, 127.0.0.1 was stuck trying to stream from it and 
> making no progress.
> Then the down node was replaced so we had:
> 127.0.0.1  MR UP     JOINING -7301836195843364181
> 127.0.0.2    MR UP     NORMAL -7263405479023135948
> 127.0.0.3    MR UP     NORMAL -7205759403792793599
> 127.0.0.5   MR UP     JOINING -7148113328562451251
> It’s confusing in the ring - the first JOINING is a genuine bootstrap, the 
> second is a replacement. We now had CAS unavailables (but no non-CAS 
> unvailables). I think it’s because the pending endpoints check thinks that 
> 127.0.0.5 is gaining a range when it’s just replacing.
> The workaround is to kill the stuck JOINING node, but Cassandra shouldn’t 
> unnecessarily fail these requests.
> It also appears like required participants is bumped by 1 during a host 
> replacement so if the replacing host fails you will get unavailables and 
> timeouts.
> This is related to the check added in CASSANDRA-8346



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