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  1. Core Server
  2. SERVER-38174

Starting replica set member standalone can lose committed writes starting in MongoDB 4.0

    • Type: Icon: Bug Bug
    • Resolution: Works as Designed
    • Priority: Icon: Major - P3 Major - P3
    • None
    • Affects Version/s: 4.0.0
    • Component/s: Replication
    • Labels:
    • ALL
    • Repl 2018-12-03

      Starting in 4.0 we do recovery at startup (for everything but the oplog) by replaying the oplog instead of by journaling. However this is not done by default if a replica set member is started standalone, so we can lose committed writes in this case. Restarting a replica set member standalone is a common documented maintenance procedure, so losing committed writes in this case seems possibly problematic. This is also a change in behavior from 3.6.

      There is an undocumented parameter to do oplog replay when started as standalone; suggest that this should be enabled by default.

            judah.schvimer@mongodb.com Judah Schvimer
            bruce.lucas@mongodb.com Bruce Lucas (Inactive)
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