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Cluster quorum in Windows 2016 RRS feed

  • Question

  • Suppose I have a multisite 4 nodes cluster, and one fsw

    each site has two nodes.

    how many nodes failure before the cluster is down.

    for example 2 prod site node down + 1 dr site node down.

    will the cluster down ?

    Wednesday, October 31, 2018 11:14 AM

All replies

  • Hi,

    You can refer to the following documentation, see if the information provided there helps.

    Understanding cluster and pool quorum

    Have a look at the Dynamic Quorum and how it works, it's well explained and also has pictures:

    https://docs.microsoft.com/en-us/windows-server/storage/storage-spaces/understand-quorum#dynamic-quorum-behavior

    Best regards,
    Leon


    Blog: https://thesystemcenterblog.com LinkedIn:

    Wednesday, October 31, 2018 11:22 AM
  • but just now I have test.

    the cluster failed.

    Wednesday, October 31, 2018 1:07 PM
  • but under dynamic vote.

    cluster should sustain for 3 nodes failed.

    Wednesday, October 31, 2018 1:10 PM
  • but under dynamic vote.  cluster should sustain for 3 nodes failed. <<< with witness

    Wednesday, October 31, 2018 1:21 PM
  • is it anything special in siteawareness feature in windows 2016  ?

    Wednesday, October 31, 2018 1:24 PM
  • "but under dynamic vote.  cluster should sustain for 3 nodes failed. <<< with witness"

    That depends upon how you lost three nodes.  Dynamic quorum is just that - it is dynamic.  But it is incrementally dynamic.  The quorum is determined from the last state of the cluster.  If you lose one node, quorum requirements will be adjusted.  If you then lose another node, quorum requirements will again be adjusted.  If you then lose a third node, quorum requirements will again be adjusted.  But, if you lose three nodes at once, the cluster will (in your case of four nodes and a file witness) originally have had a quorum of three, so there is no way for the cluster to continue operations with only two nodes because it requires three.


    tim

    Wednesday, October 31, 2018 1:43 PM
  • no   

    tim

    Wednesday, October 31, 2018 1:43 PM
  • amm…. actually what's simultaneous ??

    how long should be define as simultaneous between two nodes fail together ?

    Wednesday, October 31, 2018 2:38 PM
  • Not sure what the question is about, since the only time the word 'simultaneous' appears in this stream is in your question.

    But since you are talking about a four-node geographically dispersed cluster with two-nodes in each site, simultaneous loss of two nodes would occur when network communications are lost between the two sites.  Loss of network communications would mean two of the nodes drop out of the cluster at the same time.

     With dynamic quorum in play, it is also possible to have a similar situation with a nearly simultaneous node failure.  By this I mean that shortly after one node fails, and before the cluster software has completed its calculations for updating dynamic quorum, another node fails, it is possible that dynamic quorum may not be able to properly adjust for the second loss.

    BTW, this stream is getting very long because you keep coming up with different questions.  The format of TechNet forums is such that it is better to start a new post for a new question rather than interjecting new questions that seem to be going down a different stream of thought.


    tim


    Thursday, November 1, 2018 1:44 PM
  • "That depends upon how you lost three nodes.  Dynamic quorum is just that - it is dynamic.  But it is incrementally dynamic.  The quorum is determined from the last state of the cluster.  If you lose one node, quorum requirements will be adjusted.  If you then lose another node, quorum requirements will again be adjusted.  If you then lose a third node, quorum requirements will again be adjusted.  But, if you lose three nodes at once, the cluster will (in your case of four nodes and a file witness) originally have had a quorum of three, so there is no way for the cluster to continue operations with only two nodes because it requires three."

    I got what you mean.

    let me open another post for another questions thanks

    Friday, November 2, 2018 4:55 PM
  • Hi,

    Thanks for your updating.

    Best Regards,
    Frank


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    Monday, November 5, 2018 7:09 AM
    Moderator