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  1. Core Server
  2. SERVER-32827

Initial sync can fail when syncing a capped collection if the capped collection rolls over on the sync source

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    Details

    • Type: Bug
    • Status: Open
    • Priority: Major - P3
    • Resolution: Unresolved
    • Affects Version/s: None
    • Fix Version/s: Backlog
    • Component/s: Querying, Replication
    • Labels:
      None
    • Environment:
    • Operating System:
      ALL
    • Case:

      Description

      There is a problem with an initial sync. Several attempts have failed with the following error:
      CappedPositionLost: CollectionScan died due to position in capped collection being deleted

      The capped collections size on which the errors are occured: 30 - 100 GB
      On our workload the capped collections "capacity" (the time before each document is deleted) varies between 24 and 60 hours.

      Here are some more detailed info about the collections:

      Number of CappedPositionLost errors, collection name, capped size, capacity
      6 DB1.collection1 - 40G - 2.46week
      3 DB1.collection14 - 37G - min 56h
      3 DB1.collection2 - 30G - min 36h
      9 DB1.collection9 - 100G - min 24h

      The logs for the 7 failed attempts to perform the initial sync are attached.

      Currently there is only one alive instance is left in the replica set on our production system. Please help us to bring the replica up.

        Attachments

        1. mongo_initial_sync_20
          136 kB
        2. test.tar.gz
          1.89 MB

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              Assignee:
              backlog-server-repl Backlog - Replication Team
              Reporter:
              plsfixmymongo Sergey
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                Dates

                Created:
                Updated: