Configure vSAN with iSCSI based disks

Every time I needed to test something on vSAN in my vLab, I had to spin up some dusty nested ESXi nodes because I don’t have the proper disks in my test NUCs. But now thanks to William Lam I found a way to allow vSAN to claim iSCSI disks and let them contribute to the vSAN Disk Group! This way I can leave the nested ESXi nodes powered off and very easily test disk and host failures and play around with the Ruby vSphere Console (RVC).

Below you will see a 3 node NUC cluster without any local storage running vSAN! Pretty cool stuff!

Configure vSAN

I really hope that I don’t have to explain this, but then again better safe than sorry. 🙂

Disclaimer !! This is officially not supported by VMware, please do not use this for production or evaluation.

Now that’s out of the way let’s get started.

Configure vSAN with iSCSI disks

Before you continue present the iSCSI LUNs to your ESXi hosts. But be aware that you don’t share the LUNs across the ESXi hosts, present a dedicated set of LUNs for vSAN per ESXi host.

Open the vSphere Web Client and mark one of the presented iSCSI LUNs as a Flash device.
Click on Hosts and Clusters -> Select a Host -> Configure -> Storage Devices -> Select the iSCSI LUN to be marked as SSD -> All Actions -> Mark as Flash Disk.

And voilà! The disk device is now marked as a Flash Disk instead of a Hard Disk.

Repeat the last step for all your ESXi hosts contributing storage to the vSAN Disk Group!

The next step is to SSH to your ESXi host and run the following command to allow iSCSI disks to be claimed by vSAN.

To check if there are eligibility for VSAN usage run the following command:

It should look a little bit like this:

I have presented 3 LUNs to this ESXi host and marked 1 as Flash Disk.
3 Disks have the state: “Eligible for use by vSAN” and one of those disks has been marked as true for “IsSSD”.

Repeat the last 2 steps for all your ESXi hosts contributing storage to the vSAN Disk Group!

Now you can enable vSAN on the cluster by selecting :
Clusters and Hosts -> Select the Cluster where you want to enable vSAN on -> Configure -> Virtual SAN – General.
And just turn on vSAN!

Manually claim vSAN disks

If you run into the same issue as me and the vSAN GUI configuration doesn’t show the disks:

You will have to manually claim them. You can do this by just enabling vSAN with the manual disk selection and then SSH to the ESXi hosts and run the following command:

for example:

Repeat this step for all your ESXi hosts contributing storage to the vSAN Disk Group and behold!

vSAN with iSCSI based disks!

Enjoy 🙂

Marco van Baggum

Marco works as a Staff Consulting Architect at VMware. Want to learn more about Marco? Check out Marco's About page.

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