In this chapter, we will understand why VSAN has a relatively complex architecture, and then discuss the structure and components of VSAN.
We will then take a closer look at the finer details of how an I/O is read or written on a VSAN datastore. As we study the anatomy of a VSAN I/O, we will also closely examine the filesystem layout of VMFS-L and its key ingredients.
We will connect the dots on how this hybrid architecture and its derived filesystem structure help in implementing a granular policy specific to the objects. Furthermore, we will mildly touch upon the failure scenarios with VSAN and how the architecture enables data availability.
We will discuss the following topics in this chapter:
Anatomy of I/O
Objects, components, and witnesses
VSAN and high availability
The specific architectural changes with VSAN 6.0 are discussed in Chapter 9, What's New in VSAN 6.0?.