6.5

Table Of Contents
Introduction to Storage
Fibre Channel SAN arrays, iSCSI SAN arrays, and NAS arrays are widely used storage technologies
supported by VMware vSphere to meet dierent data center storage needs.
The storage arrays are connected to and shared between groups of servers through storage area networks.
This arrangement allows aggregation of the storage resources and provides more exibility in provisioning
them to virtual machines.
Figure 41. vSphere Data Center Physical Topology
How Virtual Machines Access Storage
A virtual disk hides the physical storage layer from the virtual machine's operating system.
Regardless of the type of storage device that your host uses, the virtual disk always appears to the virtual
machine as a mounted SCSI device. As a result, you can run operating systems that are not certied for
specic storage equipment, such as SAN, in the virtual machine.
When a virtual machine communicates with its virtual disk stored on a datastore, it issues SCSI commands.
Because datastores can exist on various types of physical storage, these commands are encapsulated into
other forms, depending on the protocol that the ESXi host uses to connect to a storage device.
Figure 4-2 depicts ve virtual machines that use dierent types of storage to illustrate the dierences
between each type.
vSphere Command-Line Interface Concepts and Examples
42 VMware, Inc.