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Hyper-V clustering & Shared Storage Q'

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  • Hyper-V clustering & Shared Storage Q'

    I have 2 Hosts (HostA, HostB) that run Server 2008 R2 Datacenter.
    I confgiured them as failover cluster and there are 2 Luns in the shared storage,
    1. Quorum
    2. OS's Lun (The Lun to save all virtual machines OS's VHD).

    I tryed to live migrate one of my machines and it worked great!
    The problem starts when I add another Lun.

    Let's say I have a Lun which is Connected to both Host's via iSCSI.
    I add to the virtual machine another Disk and directed the VHD to that Lun.
    That Lun is not in the shared storage and it is visible by both Hosts (and configured in both hosts as a simple volume).

    The Live migration now failes.
    Should this Lun also be in the shared storage in order to live migrate? (Or even quick migrate, or any migrate at all..)?

    Does it matter that in HostA the Lun is visible as "G:\" and int HostB it is "I:\"??

    Tnx in advanced,

  • #2
    Re: Hyper-V clustering & Shared Storage Q'

    After configuring the Volumes (the Lun) on the Hosts's in the same letter ("G:\"), The live migration worked..

    So I have 1 Lun which is "Shared Storage" to hold the OS's of the virtual machines,
    But I can also use a Lun which is mappe to the host and not in the shared storage..

    So why do I need a shared storage anyway?
    I can't monitor it like a regular drive, what are the advantages?

    From what I understand,
    Shared Storage is a layer above the NTFS and allows multiple nodes read\write to the same Lun.
    In my case,
    I have a Lun which is 400GB and holds all the virtual machines VHD's, so I need it to be Shared Storage.

    All my other Lun's are accessed by only one virtual (each virtual has it's own Lun's), and actualy, only one node is read\write at a time, So I don't must put these Luns in Shared Storage,

    Am I right?
    Last edited by GibliX; 14th April 2013, 22:41.


    • #3
      Re: Hyper-V clustering & Shared Storage Q'

      So have you specifcially created a Cluster Shared Volume (CSV) via Cluster Manager? How long does Live Migration take for you?


      • #4
        Re: Hyper-V clustering & Shared Storage Q'

        I created a CSV and added only the VHD for the OS's of the virtual machines.
        All other Lun's are iSCSI to both hosts.

        The live migration is loosing 2 ping tests (with ping -t test).
        and that is OK for me..
        Around 40 secondes in time concepts..


        • #5
          Re: Hyper-V clustering & Shared Storage Q'

          Whereas it is technically possible to have shared storage between two or more Hyper-V Hosts and Live Migration to still function, it is not a supported method and certainly not recommended. Sharing the LUN between two or more Hosts with them both potentially having the ability to Read/Write to it, could lead to corruption and be unreliable compared with supported solutions.

          Live Migration does not need a CSV volume to work but a CSV volume makes failover much more quicker and gives you the ability to have more than one VM in that volume and be Designed for such a requirement.

          Google tells you the advantages of a CSV volume but some key examples are below;
          • You do not have to worry about matching drive letters. I.e. You will save VMs to C:\ClusterStorage\CSV Volume name
          • The fact that it is supported for more than one VM to be placed in the volume
          • The MS cluster will handle the ownership of the CSV volume
          • If there is a network connectivity issue, there is the potential for the connection to the CSV volume to go via other systems such as another Hyper-V Host to better ensure resiliency
          When it comes to configuring the volumes to present to VMs, I tend to carry out the following.
          • If the LUN is to be used as a pass through disk, so directly connected to a specific VM, it's just presented to all of the Hyper-V Hosts and no further action is performed.
          • If the LUN is to be used as CSV volume, it's presented to all of the Hyper-V Hosts and from one of the Hyper-V Hosts, it is formatted as NTFS, it is not assigned a drive letter and then taken 'Offline'. This should still be visible when converting it to a CSV volume.
          • If the LUN is to be used as local storage for the Hyper-V Host to store VMs, you'd then present it using your usual procedure and will only be presented to one Hyper-V Host


          • #6
            Re: Hyper-V clustering & Shared Storage Q'

            Tnx, I will reconsider my implementaion.