Create Cluster VM with RDM unable to view RDM Disks

[sweehan]

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.  

[a_p_]

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

[sweehan]

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. 

[a_p_]

>>> ... 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

[nachogonzalez]

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?

[sweehan]

Yeah..It works. Thank you

[sweehan]

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"

[a_p_]

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