I received this question yesterday about material around VMFS. Of course I pointed them to the white paper Cormac recently published, which is an awesome read. But I also had this other link laying around which I forgot to share with the world. This paper is written by Satyam Vaghani (former VMware Principal Engineer, now CTO of PernixData) and is a true deepdive on VMFS and topics like locking / metadata. Do note that this paper was written in the VMFS 3.x timeframe, and as such some of the concepts might have changed.
Nevertheless, a very interesting read if you ask me! Make sure to pick up a copy here.