6.5.1

Table Of Contents
Using ESXi with iSCSI SAN 10
You can use ESXi in conjunction with a storage area network (SAN), a specialized high-speed network
that connects computer systems to high-performance storage subsystems. Using ESXi together with a
SAN provides storage consolidation, improves reliability, and helps with disaster recovery.
To use ESXi effectively with a SAN, you must have a working knowledge of ESXi systems and SAN
concepts. Also, when you set up ESXi hosts to use Internet SCSI (iSCSI) SAN storage systems, you must
be aware of certain special considerations that exist.
This chapter includes the following topics:
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iSCSI SAN Concepts
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How Virtual Machines Access Data on an iSCSI SAN
iSCSI SAN Concepts
If you are an administrator who plans to set up ESXi hosts to work with iSCSI SANs, you must have a
working knowledge of iSCSI concepts.
iSCSI SANs use Ethernet connections between computer systems, or host servers, and high-
performance storage subsystems. On the host side, the SAN components include iSCSI host bus
adapters (HBAs) or Network Interface Cards (NICs). They also include switches and routers that transport
the storage traffic, cables, storage processors (SPs), and storage disk systems.
iSCSI SAN uses a client-server architecture. The client, called iSCSI initiator, operates on your host. It
initiates iSCSI sessions by issuing SCSI commands and transmitting them, encapsulated into iSCSI
protocol, to a server. The server is known as an iSCSI target. The iSCSI target represents a physical
storage system on the network. The target can also be a virtual iSCSI SAN, for example, an iSCSI target
emulator running in a virtual machine. The iSCSI target responds to the initiator's commands by
transmitting required iSCSI data.
iSCSI Multipathing
When transferring data between the host server and storage, the SAN uses a technique known as
multipathing. With multipathing, your ESXi host can have more than one physical path to a LUN on a
storage system.
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