ESXi 8 RDM not working

[KooV]

When I add rdm disk to vm on esxi8, it doesn't work properly.

I make RDM vmdk disk by command below...

vmkfstools -z /vmfs/devices/disks/vml.01000000004b314b3532544d44202020202020202020202020484753542048 /vmfs/volumes/SSD1TB01/RDM/rdm-disk3t.vmdk

And I attached the device by adding an existing disk, but it is not attached normally as shown below.

[bhupendra81]

Similar issue here as well, appreciate any input.

[Kinnison]

Hi,

It's a known problem, which has also been discussed in this forum for some time, even quite recently, here are some references:

https://williamlam.com/2022/12/heads-up-esxi-8-0-host-client-unable-to-attach-existing-virtual-disk-...
https://communities.vmware.com/t5/ESXi-Discussions/7-0-Update-3i-can-t-attach-existing-vmdk-using-th...

Regards,
Ferdinando

[MeetingAttender]

Same exact issue here. Any update / fix is appreciated.

[Kinnison]

Hi,

It may be that a future update fixes this annoying problem affecting those who have no way to manage their systems with a vCenter object, it seems that someone has worked around this problem using "VMware Workstation Pro", others may have used other more creative and totally unsupported methods.

Regards,
Ferdinando

[MeetingAttender]

There is a workaround using vmware PowerCLI but I gives me “not supported with this license” type of error. I think it is not supported with free license. I have workstation pro though i can try with that. Do you have any link for that option?

[Kinnison]

@MeetingAttender, hi,

You may connect to you ESXi host via "VMworkstation" and then choose a VM and try to add an existing disk by editing its hardware.
Honestly, I haven't had to add an existing disk to a virtual machine for some time and since I have a running "vCenter" I wouldn't have the same problem as you.

Regards,
Ferdinando

[MeetingAttender]

Workstation Pro v16 also does not work. I get this error: The existing disk file is for a physical disk. Please select "Use a Physical Disk" to reuse an existing physical disk.

[Kinnison]

Hi,

As I told you it's been a long time since I added existing disks (including the so called RDM) to a virtual machine.
In principle, certain "rules of the game" are governed by your disk's descriptor file and thus in theory you could edit the ".vmx" file to add / change what the GUI fails to do but I prefer to avoid guessing and telling you to do things that could be more detriment than gain.

What I really don't remember is whether using an "RDM" disk adds to the ".vmx" file (or other) something more specific than a conventional "virtual disk".

Regards,
Ferdinando

[MeetingAttender]

I found out that it works when creating new VMs which is perfectly fine for my need. So I'm happy now, my problem is resolved 🙂 I tried both v7.0.3 and v8 and they both worked (meaning they accepted RDM disks with *.vmdk pointer files at the time of VM creation from web client). I could not find a way to add RDMs to an existing VM (tried web client, PowerCLI, Workstation Pro 16). Please also note that adding exisiting RDMs to existing guests worked in v6 & v6.5 for me.

References:

1. Create RDM: https://kb.vmware.com/s/article/1017530
2. This thread: https://communities.vmware.com/t5/ESXi-Discussions/ESXi-8-RDM-not-working/m-p/2942004/
3. Add RDM PowerCLI: https://williamlam.com/2022/12/heads-up-esxi-8-0-host-client-unable-to-attach-existing-virtual-disk-...
4. PowerCLI: https://www.techrepublic.com/article/how-to-manage-esxi-hosts-remotely-with-powercli/