[jira] [Commented] (CASSANDRA-6127) vnodes don't scale to hundreds of nodes

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

    [ https://issues.apache.org/jira/browse/CASSANDRA-6127?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13783372#comment-13783372 ] 

Jonathan Ellis commented on CASSANDRA-6127:
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bq. After a couple of hours, they were still flapping, had very high cpu load

To clarify, this is a bit of a mashup of multiple observations:

bq. When there was zero traffic on the cluster, we were seeing flapping without very high cpu. On smaller tests, we saw much higher cpu than expected when under load.

> vnodes don't scale to hundreds of nodes
> ---------------------------------------
>
>                 Key: CASSANDRA-6127
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6127
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>         Environment: Any cluster that has vnodes and consists of hundreds of physical nodes.
>            Reporter: Tupshin Harper
>            Assignee: Jonathan Ellis
>
> There are a lot of gossip-related issues related to very wide clusters that also have vnodes enabled. Let's use this ticket as a master in case there are sub-tickets.
> The most obvious symptom I've seen is with 1000 nodes in EC2 with m1.xlarge instances. Each node configured with 32 vnodes.
> Without vnodes, cluster spins up fine and is ready to handle requests within 30 minutes or less. 
> With vnodes, nodes are reporting constant up/down flapping messages with no external load on the cluster. After a couple of hours, they were still flapping, had very high cpu load, and the cluster never looked like it was going to stabilize or be useful for traffic.



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