vSphere Storage - ESXi 5.1 - Documentation - VMware
vSphere Storage - ESXi 5.1 - Documentation - VMware
vSphere Storage - ESXi 5.1 - Documentation - VMware
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Using <strong>ESXi</strong> with Fibre Channel SAN 3<br />
When you set up <strong>ESXi</strong> hosts to use FC SAN storage arrays, special considerations are necessary. This section<br />
provides introductory information about how to use <strong>ESXi</strong> with a FC SAN array.<br />
This chapter includes the following topics:<br />
n “Fibre Channel SAN Concepts,” on page 35<br />
n “Using Zoning with Fibre Channel SANs,” on page 36<br />
n “How Virtual Machines Access Data on a Fibre Channel SAN,” on page 37<br />
Fibre Channel SAN Concepts<br />
If you are an <strong>ESXi</strong> administrator planning to set up hosts to work with SANs, you must have a working<br />
knowledge of SAN concepts. You can find information about SANs in print and on the Internet. Because this<br />
industry changes constantly, check these resources frequently.<br />
If you are new to SAN technology, familiarize yourself with the basic terminology.<br />
A storage area network (SAN) is a specialized high-speed network that connects computer systems, or host<br />
servers, to high performance storage subsystems. The SAN components include host bus adapters (HBAs) in<br />
the host servers, switches that help route storage traffic, cables, storage processors (SPs), and storage disk<br />
arrays.<br />
A SAN topology with at least one switch present on the network forms a SAN fabric.<br />
To transfer traffic from host servers to shared storage, the SAN uses the Fibre Channel (FC) protocol that<br />
packages SCSI commands into Fibre Channel frames.<br />
To restrict server access to storage arrays not allocated to that server, the SAN uses zoning. Typically, zones<br />
are created for each group of servers that access a shared group of storage devices and LUNs. Zones define<br />
which HBAs can connect to which SPs. Devices outside a zone are not visible to the devices inside the zone.<br />
Zoning is similar to LUN masking, which is commonly used for permission management. LUN masking is a<br />
process that makes a LUN available to some hosts and unavailable to other hosts.<br />
When transferring data between the host server and storage, the SAN uses a technique known as multipathing.<br />
Multipathing allows you to have more than one physical path from the <strong>ESXi</strong> host to a LUN on a storage system.<br />
Generally, a single path from a host to a LUN consists of an HBA, switch ports, connecting cables, and the<br />
storage controller port. If any component of the path fails, the host selects another available path for I/O. The<br />
process of detecting a failed path and switching to another is called path failover.<br />
<strong>VMware</strong>, Inc. 35