Chapter 8. Connecting to Storage
ESX hosts connect to a wide variety of storage subsystems. The majority of them use block-level Small Computer System Interface (SCSI) protocols, but some use file-level protocols as well. The choice of what type of storage to use to meet which goal is up to you. The tradeoffs between the various types of storage are discussed in Chapter 3.
In this chapter, we discuss the VMware storage model. Next, we create fault-tolerant disk configurations. We then look at connecting to and the appropriate uses of various SCSI and Network Attached Storage (NAS) subsystems. Finally, the VMware File System (VMFS) is covered. So without further ado, it is time to configure and get connected to your storage.
The VMware Infrastructure 3 Layered Storage Model
VMware Infrastructure 3 (VI3) uses a layered storage model (shown in Figure 8-1) comprising your virtual machine files, a unique and robust file system called VMFS to manage access to the virtual machine files, and raw storage subsystems. The three layer storage model is as follows:
Virtual machine layer: This top layer consists of virtual machine disk files. There is one disk file for each hard drive in a virtual machine.
ESX host layer: The middle layer consists of VMFS-formatted logical unit numbers (LUNs). This allows multiple ESX hosts to access the virtual machine files.
Only one ESX host can have any virtual machine's files open at a time.
Raw storage layer: The bottom layer consists of your storage arrays, ...