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  1. Cassandra
  2. CASSANDRA-5036

Wrong description of 'setstreamthroughput' option

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    • Severity:
      Low

      Description

      There is a typo in description of 'setstreamthroughput' option. It is measured in megabits per second. Page with wrong description:
      http://www.datastax.com/docs/1.1/references/nodetool#nodetool-setstreamthroughput
      Page with right description:
      http://www.datastax.com/docs/1.1/configuration/node_configuration#stream-throughput-outbound-megabits-per-sec

      Also I want to discuss possibility to reduce default value for this option. I think that 400 Mbs is too high for common cases.

      Preface:
      This option is used only in case streams. There are two cases when streams are actual. They are rebuilding of a node and repair process. Let's skip first case and will talk only about the second. Let's imagine that we have replication factor 3.

      Cross-datacenter connectivity case:
      When we start repair process it will borrow all network channel. Let's do some calculations. You start repair on an one node, e.g. 5 node (3 remote and 2 local) should send us some data. Note that 3 of them are from remote datacenter. So 400 * 3 = 1,2 Gbs we should receive through WAN. I'm sure that it's too high.

      I suggest to make it 2 times less.

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            • Assignee:
              azotcsit Alexey Zotov
              Reporter:
              azotcsit Alexey Zotov
              Authors:
              Alexey Zotov
              Reviewers:
              Marcus Eriksson
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                Updated:
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