andvm
Enthusiast
Enthusiast

RDM disks - what are the restrictions?

Hi,

A number of RDM disks have been setup (presented from FC Storage) and presented to Virtual Machines.

A seperate LSI Logic SAS controller was used with SCSI Bus Sharing set to Physical.

The RDM disks were stored in the same directory with the VM and can see respective vmdk's and respective size (although these should just be pointers to SAN)

Are there any considerations I need to take with these VM's going forward, any restrictions?

By setting the SCSI Bus Sharing to Physical, does it mean that other VM's can also point an additional vdisk (on seperate controller) to above vmdk's?

 

 

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scott28tt
VMware Employee
VMware Employee

@andvm 

Do you know why the VMs have RDMs?

Useful references:

https://docs.vmware.com/en/VMware-vSphere/7.0/com.vmware.vsphere.storage.doc/GUID-9E206B41-4B2D-48F0...

https://kb.vmware.com/s/article/2009226

 


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VMware Training & Certification blog
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andvm
Enthusiast
Enthusiast

Not sure about its intended use which is why I would like to know why/scenarios it is used in?

One of the links was very good and with good images such as the below:

andvm_0-1605594236878.png

 

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scott28tt
VMware Employee
VMware Employee

The documentation link I posted gives a couple of examples, with many listed on the page you took that image from.

Unkess you are taking advantage of one of those benefits or use cases, stick with VMDKs.


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VMware Training & Certification blog
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andvm
Enthusiast
Enthusiast

“cluster data and quorum disks are configured as RDMs”

So as I understand RDM disks can be shared by other virtual machines simultaneously

 

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