What is VSAN?

Let's start with a simple comparison: Virtual SAN is to storage as vSphere is to compute. In other words, VSAN revolutionizes storage in a very similar way to how vSphere or virtualization, in general, revolutionized x86 servers.

VSAN has evolved through two generations so far, the first generation embedded with the vSphere 5.5.x stream (update 1 and higher) and the second generation commenced with vSphere 6.0. In this section, we will discuss the first generation to keep things simple and cover the newer features, enhancements, and architectural changes in the second generation of VSAN in Chapter 9, What's New in VSAN 6.0?.

The key features of VSAN are as follows:

• Use a combination of solid state disk (SSD) or PCIe flash devices with HDD (magnetic disks) to provide a server-based storage solution
• SSD is leveraged to optimize performance
• HDD provides the capacity

All read and write I/O will be funneled through the flash device, which will act as the first point reference...