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  1. Core Server
  2. SERVER-6696

Sharding an existent collection is losing data

    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major - P3
    • Resolution: Works as Designed
    • Affects Version/s: 2.0.6
    • Fix Version/s: None
    • Component/s: Sharding
    • Environment:
      Linux preprod 3.2.0-27-virtual #43-Ubuntu SMP Fri Jul 6 14:45:58 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux
      DISTRIB_ID=Ubuntu
      DISTRIB_RELEASE=12.04
      DISTRIB_CODENAME=precise
      DISTRIB_DESCRIPTION="Ubuntu 12.04 LTS"
    • Operating System:
      Linux

      Description

      We had an unsharded mongodb instance, which had a collection full of documents(~100M). We created an index in that collection in order to shard it.

      We enabled sharding in that node(primary), and also added another empty node in the shard grid (secondary). Everything was looking fine, but then we realize that we consistently starting losing documents from the chunk that was gettings transfered:
      http://pastebin.slackadelic.com/p/8LxWaY81.html

      In the attachment, i have both mongod running a count in the chunk criteria and one of them is losing documents and the other is not getting any documents.

      Also I had checked the logs in both mongod servers and everthing was looking fine:
      http://pastebin.slackadelic.com/p/LOsexH82.html this is from primary shard.
      http://pastebin.slackadelic.com/p/ZvgQHE51.html this is from secondary shard.

      So is that an issue? was this fixed in version 2.2 already?
      Also there is a question in SO about it: http://stackoverflow.com/questions/11768679/am-i-losing-data-when-i-am-sharding-my-existent-collection/

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              • Created:
                Updated:
                Resolved: