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6 Replies Latest reply: Feb 20, 2012 1:13 AM by 915071 RSS

Question about data lost  ?

915071 Newbie
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Question:
I have mv all *.jdb in the SN-Rep in one group(including master and slaver), but when I shutdown and restart all SNs, I also can retrieve the all the data, why this happen ? How can I simulate the data lost ?
  • 1. Re: Question about data lost  ?
    Linda Lee Journeyer
    Currently Being Moderated
    Perhaps we can help if you can describe the test scenario you are trying to create? NoSQL DB is designed to avoid losing data, so stopping and restarting any or all of the NoSQL DB nodes will not result in data loss.
  • 2. Re: Question about data lost  ?
    915071 Newbie
    Currently Being Moderated
    I want test backup and recovery mechanism, so I need to test data lost and I know the key/values data is contained in *.jdb, and I rm all *.jdb files, why I also can retrieve the data ? Why can this happen ? And after some tests, I guess snapshot can't backup logs(redo or undo logs like oracle), so the backup is incomplete ?
  • 3. Re: Question about data lost  ?
    524761 Journeyer
    Currently Being Moderated
    Do you have just one group in your KVStore, or multiple groups? If you only removed one group's files, perhaps the data you were looking for was in other groups?
  • 4. Re: Question about data lost  ?
    915071 Newbie
    Currently Being Moderated
    You mean that if I rm all data files(*.jdb) in one group when there is only one group, it should be lose data and I can't retrieve information ?
    Could you tell me how to set multi-groups for one store ? What is the command ?

    Thanks.
  • 5. Re: Question about data lost  ?
    524761 Journeyer
    Currently Being Moderated
    foreversunyao wrote:
    You mean that if I rm all data files(*.jdb) in one group when there is only one group, it should be lose data and I can't retrieve information ?
    I should think so, yes. Assuming that the system is shut down at the time you remove the files.
    Could you tell me how to set multi-groups for one store ? What is the command ?
    The system decides on the number of groups automatically, based on the supplied Storage Nodes and the specified Replication Factor. For example, if you were to supply 6 Storage Nodes, and specify a Replication Factor of 3, the system would create 2 groups.
  • 6. Re: Question about data lost  ?
    915071 Newbie
    Currently Being Moderated
    Thanks

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