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  • 1.  Create Cluster VM with RDM unable to view RDM Disks

    Posted Aug 18, 2021 11:29 AM

    I need to build a new MS cluster server on my vSphere 7 environment. I've mapped 1 RDM disk with 200GB and another with 500GB on the hosts. I created the first VM mapped with RDM without problem. But when create the second VM I want to add the same RDM disks I not able to find the same RDM Disk or the same LUNid of the RDM disk. 

    I test back on the vSphere 6 environment using vSphere client have no issue adding the same RDM disks on the VMs.  



  • 2.  RE: Create Cluster VM with RDM unable to view RDM Disks

    Posted Aug 18, 2021 12:04 PM

    How are you trying to add the RDM to the second node?
    Once an RDM has been added to a VM, you'll have to use the "Use existing virtual disk" option for additional VMs, and select the .vmdk descriptor file that's been created with adding the RDM to the first VM.

    André



  • 3.  RE: Create Cluster VM with RDM unable to view RDM Disks

    Posted Aug 18, 2021 12:50 PM

    Add existing disk works. But I wanted to simulate the same VM config as on vSphere 6.0 environment where both VM are added the same RDM Disks. 



  • 4.  RE: Create Cluster VM with RDM unable to view RDM Disks

    Posted Aug 18, 2021 01:01 PM

    >>> ... where both VM are added the same RDM Disks.
    Using the same descriptor/mapping file, means that both VMs use the same LUN.

    Mapping the same RDM LUN using different descriptor/mapping files may cause issues.
    In case you want to do this anyway - taking possible data corruption into account - see e.g. https://kb.vmware.com/s/article/1010513

    André



  • 5.  RE: Create Cluster VM with RDM unable to view RDM Disks

    Posted Aug 22, 2021 06:01 AM

    Hi hope you are doing fine?
    How is the SCSI bus sharing configured on the VMs?
    did you try mapping an existing VMDK and selecting the RDM pointers?



  • 6.  RE: Create Cluster VM with RDM unable to view RDM Disks

    Posted Aug 27, 2021 09:56 AM

    Yeah..It works. Thank you



  • 7.  RE: Create Cluster VM with RDM unable to view RDM Disks

    Posted Aug 28, 2021 12:58 AM

    enable Multi-writer is a must? Because if not enable multi-writer, I can only power up one of the node only and the other not able to power up. It will show error "File system specific implementation of Ioctl[file] failed Failed to start the virtual machine. Module 'Disk' power on failed. Cannot open the disk '/vmfs/volumes/vm file path/vmname.vmdk' or one of the snapshot disks it depends on"



  • 8.  RE: Create Cluster VM with RDM unable to view RDM Disks

    Posted Aug 28, 2021 10:39 AM

    Do NOT enable "Multi Writer" for an WSFC. WSFC is a "shared-nothing" cluster, where only one node at a time must access a given disk/file system. Otherwise you'd end up with file system corruption.

    Please see https://docs.vmware.com/en/VMware-vSphere/7.0/vsphere-esxi-vcenter-server-70-setup-wsfc.pdf (pages 20ff) for how to add RDMs to the VMs for a CAB "Cluster-across-Boxes" configuration.

    André