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Date: Tue, 12 Nov 2013 21:26:20 +0000 (UTC)
From: "Quentin Conner (JIRA)" <jira@apache.org>
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Subject: [jira] [Updated] (CASSANDRA-6127) vnodes don't scale to hundreds of
 nodes
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     [ https://issues.apache.org/jira/browse/CASSANDRA-6127?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Quentin Conner updated CASSANDRA-6127:
--------------------------------------

    Attachment: flaps-vs-tokens.png

Flapping occurs with vnodes or without.  Please see attached.

Using vnodes appears to exacerbate, possibly with longer messages, probably with higher cpu utilization.  Either would delay the timestamp for the Failure Detector interarrival time.

> 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
>         Attachments: 2013-11-05_18-04-03_no_compression_cpu_time.png, 2013-11-05_18-09-38_compression_on_cpu_time.png, 6000vnodes.patch, AdjustableGossipPeriod.patch, delayEstimatorUntilStatisticallyValid.patch, flaps-vs-tokens.png
>
>
> 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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