Are your servers that you are going to host Moodle also on vSphere? First time that you had mentioned it. If so than you do not need to worry about a SAN.
Create 2 New VMs for Web Servers with basic 20GB Disks for the OS then add a new hard disk to one of the VMs in vSphere BUT must be configured correctly for sharing across multiple VMs.
So, Edit Settings > Add > Hard Disk > Create a new virtual disk > Choose size and choose "Thick Provision Eager Zeroed" > under "Virtual Device Node" choose a "SCSI (1:0)" then finish.
After the disk has been zero'd out go back into "Edit Settings" > click the new SCSI controller 1 and choose "Physical" Virtual disks can be shared between virtual machines on any server.
Edit the settings for the 2nd VM and choose add hard disk, choose existing, browse to where you created the disk for VM 1 , make sure you assign it the same SCSI (1:0).
You now have a virtual hard disk shared between your machines that you can then setup OCFS2 on.
If not, let me know what is available to you, like your setup so I can get a clear picture.