Networked storage consists of external storage systems that your ESXi host uses to store virtual machine files remotely. Typically, the host accesses these systems over a high-speed storage network.
Networked storage devices are shared. Datastores on networked storage devices can be accessed by multiple hosts concurrently. ESXi supports multiple networked storage technologies.
In addition to traditional networked storage that this topic covers, VMware supports virtualized shared storage technologies. These technologies transform the internal storage resources of your ESXi hosts into shared storage that provides such capabilities as High Availability and vMotion for virtual machines. For details, see Working with Virtual SAN or the vSphere Storage Appliance documentation.
The same LUN cannot be presented to an ESXi host or multiple hosts through different storage protocols. To access the LUN, hosts must always use a single protocol, for example, either Fibre Channel only or iSCSI only.
Fibre Channel (FC)
Stores virtual machine files remotely on an FC storage area network (SAN). FC SAN is a specialized high-speed network that connects your hosts to high-performance storage devices. The network uses Fibre Channel protocol to transport SCSI traffic from virtual machines to the FC SAN devices.
To connect to the FC SAN, your host should be equipped with Fibre Channel host bus adapters (HBAs). Unless you use Fibre Channel direct connect storage, you need Fibre Channel switches to route storage traffic. If your host contains FCoE (Fibre Channel over Ethernet) adapters, you can connect to your shared Fibre Channel devices by using an Ethernet network.
Fibre Channel Storage depicts virtual machines using Fibre Channel storage.
In this configuration, a host connects to a SAN fabric, which consists of Fibre Channel switches and storage arrays, using a Fibre Channel adapter. LUNs from a storage array become available to the host. You can access the LUNs and create datastores for your storage needs. The datastores use the VMFS format.
For specific information on setting up the Fibre Channel SAN, see Using ESXi with Fibre Channel SAN.
Internet SCSI (iSCSI)
Stores virtual machine files on remote iSCSI storage devices. iSCSI packages SCSI storage traffic into the TCP/IP protocol so that it can travel through standard TCP/IP networks instead of the specialized FC network. With an iSCSI connection, your host serves as the initiator that communicates with a target, located in remote iSCSI storage systems.
ESXi offers the following types of iSCSI connections:
Your host connects to storage through a third-party adapter capable of offloading the iSCSI and network processing. Hardware adapters can be dependent and independent.
Your host uses a software-based iSCSI initiator in the VMkernel to connect to storage. With this type of iSCSI connection, your host needs only a standard network adapter for network connectivity.
You must configure iSCSI initiators for the host to access and display iSCSI storage devices.
iSCSI Storage depicts different types of iSCSI initiators.
In the left example, the host uses the hardware iSCSI adapter to connect to the iSCSI storage system.
In the right example, the host uses a software iSCSI adapter and an Ethernet NIC to connect to the iSCSI storage.
iSCSI storage devices from the storage system become available to the host. You can access the storage devices and create VMFS datastores for your storage needs.
For specific information on setting up the iSCSI SAN, see Using ESXi with iSCSI SAN.
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.
ESXi does not support the delegate user functionality that enables access to NFS volumes using non-root 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.
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.