vSphere Storage - ESXi 5.1 - Documentation - VMware

Network-attached Storage (NAS)
Stores virtual machine files on remote file servers accessed over a standard TCP/IP network. The NFS client
built into ESXi uses Network File System (NFS) protocol version 3 to communicate with the NAS/NFS servers.
For network connectivity, the host requires a standard network adapter.
NOTE ESXi does not support the delegate user functionality that enables access to NFS volumes using nonroot
credentials.
NFS Storage depicts a virtual machine using the NFS volume to store its files. In this configuration, the host
connects to the NFS server, which stores the virtual disk files, through a regular network adapter.
Figure 1-4. NFS Storage
Host
virtual
machine
NFS
ethernet
NIC
LAN
NAS appliance
Shared Serial Attached SCSI (SAS)
Stores virtual machines on direct-attached SAS storage systems that offer shared access to multiple hosts. This
type of access permits multiple hosts to access the same VMFS datastore on a LUN.
Target and Device Representations
Chapter 1 Introduction to Storage
In the ESXi context, the term target identifies a single storage unit that the host can access. The terms device
and LUN describe a logical volume that represents storage space on a target. Typically, the terms device and
LUN, in the ESXi context, mean a storage volume presented to the host from a storage target and available for
formatting.
Different storage vendors present the storage systems to ESXi hosts in different ways. Some vendors present
a single target with multiple storage devices or LUNs on it, while others present multiple targets with one
LUN each.
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