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  1. Couchbase Server
  2. MB-62786

Partition skew(both active and replica) without any topology change

Details

    • Bug
    • Resolution: Unresolved
    • Critical
    • 7.6.4
    • 7.6.2, 7.2.6, 7.6.4
    • fts
    • 7.6.2 build 3721

    Description

      Steps:

      1. Create 3 node cluster with 2 nodes as fts nodes
      2. Create 3 fts indexes, 1 with 18 partitions and other with 3 each.

      Seeing a partition skew for index1, instead of 9-9 partitions in each node it is 10-8.

      FTS NODES: [ip:172.23.120.23 port:8091 ssh_username:root, ip:172.23.121.140 port:8091 ssh_username:root]
      Actives:
          172.23.120.23:8094 : 12
          172.23.121.140:8094 : 12
      Replicas:
          172.23.121.140:8094 : 12
          172.23.120.23:8094 : 12
      Actual number of index partitions in cluster: 48
      Expected number of index partitions in cluster: 48
      Indexes: 3
          default_index_1 :: maxPartitionsPerPIndex: 57, indexPartitions: 18, numReplicas: 1
          default_index_2 :: maxPartitionsPerPIndex: 342, indexPartitions: 3, numReplicas: 1
          default_index_3 :: maxPartitionsPerPIndex: 342, indexPartitions: 3, numReplicas: 1
      Index actives distribution:
          Index: default_index_1
              172.23.120.23:8094 : 10
              172.23.121.140:8094 : 8
          Index: default_index_2
              172.23.121.140:8094 : 2
              172.23.120.23:8094 : 1
          Index: default_index_3
              172.23.121.140:8094 : 2
              172.23.120.23:8094 : 1
      Index replicas distribution:
          Index: default_index_1
              172.23.121.140:8094 : 10
              172.23.120.23:8094 : 8
          Index: default_index_2
              172.23.120.23:8094 : 2
              172.23.121.140:8094 : 1
          Index: default_index_3
              172.23.120.23:8094 : 2
              172.23.121.140:8094 : 1 

      This is happening with replica partitions also.

      Steps:

      1. Create 3 node cluster with 2 nodes as fts nodes
      2. Create 3 fts indexes with 1 partition each
      3. Update partition count to 18,3,3

      Seeing that active partitions are fine but replica partitions are having a skew.

      Actives:
              172.23.120.23:8094 : 8
              172.23.122.68:8094 : 8
              172.23.107.56:8094 : 8
      Replicas:
              172.23.122.68:8094 : 9
              172.23.107.56:8094 : 8
              172.23.120.23:8094 : 7
      Actual number of index partitions in cluster: 48
      Expected number of index partitions in cluster: 48
      Indexes: 3
              n2 :: maxPartitionsPerPIndex: 57, indexPartitions: 18, numReplicas: 1
              n2-copy :: maxPartitionsPerPIndex: 342, indexPartitions: 3, numReplicas: 1
              n2-copy-copy :: maxPartitionsPerPIndex: 342, indexPartitions: 3, numReplicas: 1Index actives distribution:
              Index: n2-copy-copy
                      172.23.107.56:8094 : 1
                      172.23.120.23:8094 : 1
                      172.23.122.68:8094 : 1
              Index: n2
                      172.23.120.23:8094 : 6
                      172.23.107.56:8094 : 6
                      172.23.122.68:8094 : 6
              Index: n2-copy
                      172.23.120.23:8094 : 1
                      172.23.122.68:8094 : 1
                      172.23.107.56:8094 : 1
      Index replicas distribution:
              Index: n2-copy
                      172.23.122.68:8094 : 2
                      172.23.120.23:8094 : 1
              Index: n2-copy-copy
                      172.23.120.23:8094 : 1
                      172.23.122.68:8094 : 1
                      172.23.107.56:8094 : 1
              Index: n2
                      172.23.120.23:8094 : 5
                      172.23.107.56:8094 : 7
                      172.23.122.68:8094 : 6
       

      However on triggering a rebalance via cli removed the skew

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            sarthak.dua Sarthak Dua
            sarthak.dua Sarthak Dua
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              Created:
              Updated:

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