6.0.1

Table Of Contents
How Virtual Machines Access Storage
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.
ESXi supports Fibre Channel (FC), Internet SCSI (iSCSI), Fibre Channel over Ethernet (FCoE), and NFS
protocols. Regardless of the type of storage device your host uses, the virtual disk always appears to the
virtual machine as a mounted SCSI device. The virtual disk hides a physical storage layer from the virtual
machine’s operating system. This allows you to run operating systems that are not certied for specic
storage equipment, such as SAN, inside the virtual machine.
The following graphic depicts ve virtual machines using dierent types of storage to illustrate the
dierences between each type.
Figure 16. Virtual machines accessing different types of storage
iSCSI array NAS appliancefibre array
Host
VMFS
SCSI
VMFS VMFS NFS
virtual
machine
virtual
machine
virtual
machine
virtual
machine
virtual
machine
SAN LAN LAN LAN
iSCSI
HBA
fibre
channel
HBA
ethernet
NIC
ethernet
NIC
software
adapter
requires TCP/IP connectivity
Key
physical
disk
datastore
virtual
disk
N This diagram is for conceptual purposes only. It is not a recommended conguration.
Comparing Types of Storage
Whether certain vSphere functionality is supported might depend on the storage technology that you use.
The following table compares networked storage technologies that ESXi supports.
Table 14. Networked Storage that ESXi Supports
Technology Protocols Transfers Interface
Fibre Channel FC/SCSI Block access of data/LUN FC HBA
Fibre Channel over
Ethernet
FCoE/SCSI Block access of data/LUN
n
Converged Network Adapter (hardware
FCoE)
n
NIC with FCoE support (software FCoE)
vSphere Storage
24 VMware, Inc.