VMware vSphere

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  • 1.  RDM Disks in Failover Clustering

    Posted Sep 05, 2023 02:38 PM

    Hello everyone,

    I have a virtual machine that has RDM disks attached in virtual mode, and configured with the Failover Clustering Role at the operating system level. The client wants to convert those RDMs to VMDK

    For that, use vmware converter, it converts the RDM into VMDK without problems, however when validating the disks in the failover clustering, they appear as blocked with the following error.


    Or would it be advisable to disable failvoer clustering before migrating the cm with vmware converter? and then when lifting in the other site, activate the river, from failvoer clustering?

    Any suggestions so that I can see those disks in the failover clustering.





  • 2.  RE: RDM Disks in Failover Clustering

    Posted Sep 05, 2023 04:11 PM

    What will work depends on your environment. Please take a look at https://kb.vmware.com/s/article/79616 which lists the requiremenst for supported configuration.


  • 3.  RE: RDM Disks in Failover Clustering

    Posted Sep 05, 2023 09:41 PM

    Hello  ,

    There are 2 ways to convert RDM to VMDK.

    1. With Vmware Convertor.

    2. With use of Storage Migration and selecting the disk type as Virtual Disk.



    - both requires disk to be present only on 1 VM.

    - if we convert RDM to vmdk then we cannot convert the vmdk back to RDM. Its a 1 way street.

    - if we use vmdk for sharing then your both nodes have to be on 1 Esxi host as vmdk multi-writer sharing only supports Cluster In Box configuration which means that both nodes of cluster needs to be on same Esxi host.


    Please check the above things and only then proceed to convert RDM into VMDK as RDMs have advantages over vmdks.