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Windows 2016 - Failover Cluster - Quorum Question

    Question

  • If I do not dedicate a quorum drive in cluster manager what are the consequences? I have a 8 hosts cluster with 2 10TB's LUNS attached as "cluster shared volumes" and everything (live migration, host failover) seems to be working just fine. I did not designate a quorum or a witness during setup.

    What am I missing?

    Thanks


    Thursday, October 18, 2018 7:05 PM

Answers

  • If you Don't configure a Quorum / witness in a 8-nodes cluster, it means that the cluster needs a majority of nodes up and running to keep the cluster running.  So if you do a maintenance on your cluster, you cannot put offline more than 3 nodes at the time.  But keep in mind that if during your maintenance you have an issue with another cluster node, your cluster will be down.

    See this article --> https://docs.microsoft.com/en-us/windows-server/storage/storage-spaces/understand-quorum


    This posting is provided AS IS without warranty of any kind

    • Marked as answer by Heybuzzz76 Thursday, October 18, 2018 10:30 PM
    Thursday, October 18, 2018 7:34 PM
  • Hi

    Pools are indeed used in Failover Clustering when using Storage Space Direct drives. Back-end connected Fibre LUNs are not part of the Storage Subsystem of a Failover Cluster and therefore do not represent themselves in that Pool. Unless there is a tight integration with the back-end Storage Array using plugins/providers.

    In your case you can skip the Pools in FCM.

    Greetings,
    Richard

    • Marked as answer by Heybuzzz76 Friday, October 19, 2018 11:21 AM
    Friday, October 19, 2018 10:04 AM
  • "So if one does not create a quorum/witness drive where does Microsoft store the cluster data at?"

    Each node keeps track on its own.  If a share witness is used, there is no 'external' storage of the cluster database.  If a disk witness is used, a copy of the cluster database is stored on the disk witness.  The disk witness provides a slightly better model in case of major disasters for restoring a cluster because it has the latest copy of the cluster database that all nodes can refer to, whereas when using a share witness, such a 'backup' is not available.

    The other benefit of a witness, share or disk, is dynamic quorum.  It automatically adjusts quorum (quorum is different from witness) to allow for continued operations over the course of more failures.


    tim

    • Marked as answer by Heybuzzz76 Friday, October 19, 2018 4:42 PM
    Friday, October 19, 2018 2:18 PM

All replies

  • If you Don't configure a Quorum / witness in a 8-nodes cluster, it means that the cluster needs a majority of nodes up and running to keep the cluster running.  So if you do a maintenance on your cluster, you cannot put offline more than 3 nodes at the time.  But keep in mind that if during your maintenance you have an issue with another cluster node, your cluster will be down.

    See this article --> https://docs.microsoft.com/en-us/windows-server/storage/storage-spaces/understand-quorum


    This posting is provided AS IS without warranty of any kind

    • Marked as answer by Heybuzzz76 Thursday, October 18, 2018 10:30 PM
    Thursday, October 18, 2018 7:34 PM
  • Thanks for the info...

    So if one does not create a quorum/witness drive where does Microsoft store the cluster data at?

    Thanks!

    Thursday, October 18, 2018 10:33 PM
  • I might as well ask about Pools too...

    Under "storage" I see the ability to create a storage "pool". Is this feature mainly for combining storage space direct drives?

    In my scenario I have fiber LUNs presented and I have them online as Cluster Shared Volumes. 

    What advantages do using Pools offer?

    Thanks

    Thursday, October 18, 2018 10:53 PM
  • Hi

    Pools are indeed used in Failover Clustering when using Storage Space Direct drives. Back-end connected Fibre LUNs are not part of the Storage Subsystem of a Failover Cluster and therefore do not represent themselves in that Pool. Unless there is a tight integration with the back-end Storage Array using plugins/providers.

    In your case you can skip the Pools in FCM.

    Greetings,
    Richard

    • Marked as answer by Heybuzzz76 Friday, October 19, 2018 11:21 AM
    Friday, October 19, 2018 10:04 AM
  • "So if one does not create a quorum/witness drive where does Microsoft store the cluster data at?"

    Each node keeps track on its own.  If a share witness is used, there is no 'external' storage of the cluster database.  If a disk witness is used, a copy of the cluster database is stored on the disk witness.  The disk witness provides a slightly better model in case of major disasters for restoring a cluster because it has the latest copy of the cluster database that all nodes can refer to, whereas when using a share witness, such a 'backup' is not available.

    The other benefit of a witness, share or disk, is dynamic quorum.  It automatically adjusts quorum (quorum is different from witness) to allow for continued operations over the course of more failures.


    tim

    • Marked as answer by Heybuzzz76 Friday, October 19, 2018 4:42 PM
    Friday, October 19, 2018 2:18 PM