[jira] [Resolved] (CASSANDRA-9059) read_repair slows down the response for mulit-dc setup with LOCAL_QUORUM read CL

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

     [ https://issues.apache.org/jira/browse/CASSANDRA-9059?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Philip Thompson resolved CASSANDRA-9059.
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    Resolution: Duplicate

> read_repair slows down the response for mulit-dc setup with LOCAL_QUORUM read CL
> --------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-9059
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-9059
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>         Environment: CentOS 6.6 , Cassandra 2.0.8
>            Reporter: Wei Zhu
>             Fix For: 2.0.14
>
>         Attachments: coodidatorreadlatency_after.png, coodidatorreadlatency_before.png
>
>
> We have two DC setup for the Cassandra Cluster. 7 nodes each, RF = 3. We setup CL as LOCAL_QUORUM for both read and write. 
> We have noticed that 95th percentile coordiantorReadLatency is at 60ms range. 
> We modified read_repair_chance for this CF to 0.0 from the default 0.1, we see dramatic improvements for the coordiantorReadLatency. It went down to 10ms. 
> I suspect read_repair somehow waits/blocks the response from other DC which shouldn't happen.



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