After verifying the network connectivity, we can now enable VSAN on the cluster. This is pretty simple, from the vSphere Client, select the cluster and click on Configure as shown below.
Select the options as needed. Enabling Deduplication and Compression is a good thing as this reduces the used space on the vsanDatastore and thus reducing the data that needs to be copied should there be a failure. To configure 2 Node Direct Connect VSAN, you need to select the ‘Configure two hostvSAN Cluster’ and click Next.
Now ensure the VMkernel validation is passed, this is absolutely necessary to proceed further. Click Next
The next screen allows you to select the disks that you want to contribute to Capacity and Cache. In All falsh configuration, the disks are automatically claimed and VSAN does the intelligent selection for you. Usually the small sized disks are used for cache and others for capacity. You can set the disks to Do not Claim if you want them to use as spare in case of failure but it would be good to use all of them as we will have redundancy on the second node.
Now select the witness host and click Next.
In case of physical witness host, depending on the size of your Witness Deployment, you would need to select the disks needed for Capacity and Cache. Since we are using the appliance, we get two disks with sizes 15GB and 10GB. Select the 10GB disk for cache and 15GB for the capacity. Click Next
Review the settings and click Finish.
In the Recent Tasks, you can see the disk groups created and disks being added to the disk groups.
Also depending on the version of VSAN you are on, you should see the vsanDatastore being formatted. Pre 6.6 will have a On Disk Format 3 and 6.6 and above will have a version 5. Version 5 of On-Disk Format enables many features like Encrytion and Per Site Policies for Stretched Clusters.
That should complete your basic VSAN configuration.