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  1. Cassandra
  2. CASSANDRA-9059

read_repair slows down the response for mulit-dc setup with LOCAL_QUORUM read CL

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    Details

    • Type: Bug
    • Status: Resolved
    • Priority: Normal
    • Resolution: Duplicate
    • Fix Version/s: 2.0.15
    • Component/s: None
    • Labels:
      None
    • Environment:

      CentOS 6.6 , Cassandra 2.0.8

    • Severity:
      Normal
    • Since Version:

      Description

      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.

        Attachments

        1. coodidatorreadlatency_after.png
          116 kB
          Wei Zhu
        2. coodidatorreadlatency_before.png
          147 kB
          Wei Zhu

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              • Assignee:
                Unassigned
                Reporter:
                weizhu Wei Zhu
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                Dates

                • Created:
                  Updated:
                  Resolved: