Presenting SSD storage in nested VMware vSphere ESXi

SSD vmware VSAN vSphere

There are a couple of ways that you can present SSD storage in nested VMware vSphere ESXi installations.

You may need to do this because you want to lab out VSAN of which SSD is a requirement within a VMware Workstation environment. As a rule if you create a VMDK for the ESXi instance that is actually SSD backed the nested ESXi instance will recognise this and you will not actually need to do anything. But what if it does not or your do not have SSD available to you.

Depending on the version of vSphere that you use this can be a simple single click operation or an addition to the VMX file for the ESXi vm.

vSphere 6

Those of you who are running vSphere 6 in your lab there is a handy Tag feature which will allow you to mark a hard disk as SSD/Flash even though ESXi has not detected it as such to begin with.

1/ From within the Web GUI click on the host in question and then navigate to the Manage tab and then select Storage and then the Storage Devices menu.

2/ Select the disk you want to specify as a VSAN compatible disk and you will notice a new blue icon with an F in it!

3/ Clicking on that allows you to mark the select disk as a Flash disk (or back to HDD if you feel so inclined).


Thats it your done. Simples!


vSphere 5.5 and older


For older versions of vSphere without the Mark as SSD/Flash capability a little bit more tinkering is involved.

Heres a screenshot of a ESXi disk I’ve added from an old SATA spinning disk I have and have created a small 2GB virtual disk and attached it to the nested ESXi instance.


Firstly we’ll need to know the SCSI ID of the VMDK disk at the VMware Workstation level.

1/ Goto Edit Settings in your ESXi virtual machine and select the virtual hard disk in question.
2/ Click the Advanced button at the bottom right hand side of the settings window.


3/ Take note of the SCSI ID of the virtual hard disk and then click ok and then exit the settings dialog box.
4/If not already shutdown the ESXi virtual machine.


5/ Now edit the nested ESXi’s vmx configuration file and Add “SCSI0:5.virtualSSD = 1” into the file. Where SCSI0:5 is enter the SCSI ID you have taken note of in step three.
6/ Save and close the vmx file


7/ Start the ESXi virtual machine and once it has booted and reconnected to vCenter you should see that the disk is now marked as Flash storage.


Thats it all done. As mentioned this is very useful for labbing out things like VSAN where it needs to be able to see SSD/Flash type storage and when a nested ESXi environment is having trouble passing through an SSD or you do not have one. Of course by marking a spinning disk as SSD/Flash you cannot expect any sort of performance out of it but the options are there if you need them.

Author: Dale Scriven

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