If you are an ESX/ESXi administrator planning to set up ESX/ESXi hosts to work with SANs, you must have a working knowledge of SAN concepts. You can find information about SANs in print and on the Internet. Because this industry changes constantly, check these resources frequently.

If you are new to SAN technology, familiarize yourself with the basic terminology.

A storage area network (SAN) is a specialized high-speed network that connects computer systems, or host servers, to high performance storage subsystems. The SAN components include host bus adapters (HBAs) in the host servers, switches that help route storage traffic, cables, storage processors (SPs), and storage disk arrays.

A SAN topology with at least one switch present on the network forms a SAN fabric.

To transfer traffic from host servers to shared storage, the SAN uses Fibre Channel (FC) protocol that packages SCSI commands into Fibre Channel frames.

To restrict server access to storage arrays not allocated to that server, the SAN uses zoning. Typically, zones are created for each group of servers that access a shared group of storage devices and LUNs. Zones define which HBAs can connect to which SPs. Devices outside a zone are not visible to the devices inside the zone.

Zoning is similar to LUN masking, which is commonly used for permission management. LUN masking is a process that makes a LUN available to some hosts and unavailable to other hosts. Usually, LUN masking is performed at the SP or server level.