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Disk witness size and quantity for S2D cluster RRS feed

  • Question

  • Hi,

    What should be size o quorum? Assuming cluster disk space is 2 TB, what would be size of the shared folder, does it has to be similar to the storage capacity?

    Also, for a 2 node cluster, quorum or disk witness should be one (minimum), do we have maximum as well?

     
    Tuesday, May 19, 2020 5:50 PM

Answers

  • A failover cluster with one one node destroys its purpose, so I would say no, you will need at least two nodes.

    You can also use a file share as quorum and have the file share for example hosted on another cluster, or then a standalone server, as long as its not dependant of the cluster where it will serve as a witness.


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    • Marked as answer by -OSD- Friday, May 22, 2020 6:10 PM
    Tuesday, May 19, 2020 9:25 PM
  • Hi,

    >>Assuming cluster disk space is 2 TB, what would be size of the shared folder, does it has to be similar to the storage capacity?

    It is recommended that you configure the quorum disk size to be 500 MB; this size is the minimum required for an efficient NTFS partition. But there is no recommended size for file share witness size.

    The theory behind a File Share Witness is to employ a third party – usually located in a third physical location – to serve as an additional vote so that a quorum can be reached and cluster operations can continue to run.

    A File Share Witness is similar to a cluster quorum disk, but does not store cluster configuration data. However, the file share does include information about which version of the cluster configuration database is most current.

    For detail information, please refer to this:

    https://support.microsoft.com/en-us/help/280345/quorum-drive-configuration-information

    https://searchservervirtualization.techtarget.com/definition/File-Share-Witness-FSW

    >>Also, for a 2 node cluster, quorum or disk witness should be one (minimum), do we have maximum as well?

    One disk or file share witness is OK, for S2D cluster, we cannot configure disk witness, but for no S2D cluster, disk witness is better than file share witness.

    Best Regards,

    Daniel


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    • Marked as answer by -OSD- Friday, May 22, 2020 6:10 PM
    Wednesday, May 20, 2020 1:56 AM
    Moderator

All replies

  • Hi,

    The recommendation of the quorum disk size is 500 MB, this size is the minimum required for an efficient NTFS partition.

    https://support.microsoft.com/en-us/help/280345/quorum-drive-configuration-information

    One quorum (disk witness) is enough, but it is also recommended that you configure some form of fault tolerance at the hardware level to be used for the quorum drive.

    Best regards,
    Leon


    Blog: https://thesystemcenterblog.com LinkedIn:

    Tuesday, May 19, 2020 5:56 PM
  • Hi and thanks for reply, appreciated.

    Having a dedicated server to host the "shared drive" may result inefficient resource utilization as 500 MB is only required for quorum. Can we eliminate this extra node ans host the share of Domain Controller (Primary) and Secondary (this will also provide fault tolerance). Makes any logic or ...?

    Tuesday, May 19, 2020 9:18 PM
  • A failover cluster with one one node destroys its purpose, so I would say no, you will need at least two nodes.

    You can also use a file share as quorum and have the file share for example hosted on another cluster, or then a standalone server, as long as its not dependant of the cluster where it will serve as a witness.


    Blog: https://thesystemcenterblog.com LinkedIn:

    • Marked as answer by -OSD- Friday, May 22, 2020 6:10 PM
    Tuesday, May 19, 2020 9:25 PM
  • Hi,

    >>Assuming cluster disk space is 2 TB, what would be size of the shared folder, does it has to be similar to the storage capacity?

    It is recommended that you configure the quorum disk size to be 500 MB; this size is the minimum required for an efficient NTFS partition. But there is no recommended size for file share witness size.

    The theory behind a File Share Witness is to employ a third party – usually located in a third physical location – to serve as an additional vote so that a quorum can be reached and cluster operations can continue to run.

    A File Share Witness is similar to a cluster quorum disk, but does not store cluster configuration data. However, the file share does include information about which version of the cluster configuration database is most current.

    For detail information, please refer to this:

    https://support.microsoft.com/en-us/help/280345/quorum-drive-configuration-information

    https://searchservervirtualization.techtarget.com/definition/File-Share-Witness-FSW

    >>Also, for a 2 node cluster, quorum or disk witness should be one (minimum), do we have maximum as well?

    One disk or file share witness is OK, for S2D cluster, we cannot configure disk witness, but for no S2D cluster, disk witness is better than file share witness.

    Best Regards,

    Daniel


    Please remember to mark the replies as answers if they help.
    If you have feedback for TechNet Subscriber Support, contact

    • Marked as answer by -OSD- Friday, May 22, 2020 6:10 PM
    Wednesday, May 20, 2020 1:56 AM
    Moderator
  • Hi,

    Can we host this share on domain controllers (I do have primary and secondary DCs), good practice?

    Wednesday, May 20, 2020 7:06 PM
  • Yes you can, not the best practice but it's possible, if you have a file server you could host it there.



    Blog: https://thesystemcenterblog.com LinkedIn:

    Wednesday, May 20, 2020 7:13 PM