Install Windows Server 2012 R2 - MCSA Windows Server 2012 R2: Installation and Configuration Study Guide - page 42

iSCSI was developed to allow block-level access to a storage device over a network. This
is different from using a network attached storage (NAS) device that connects through the
use of Common Internet File System (CIFS) or Network File System (NFS).
Block-level access is important to many applications that require direct access to storage.
Microsoft Exchange and Microsoft SQL are examples of applications that require direct
access to storage.
By being able to leverage the existing network infrastructure, iSCSI was also developed
as an alternative to Fibre Channel storage by alleviating the additional hardware costs
associated with a Fibre Channel storage solution.
iSCSI also has another advantage over Fibre Channel in that it can provide security for
the storage devices. iSCSI can use Challenge Handshake Authentication Protocol (CHAP
or MS-CHAP) for authentication and Internet Protocol Security (IPsec) for encryption.
Windows Server 2012 R2 is able to connect an iSCSI storage device out of the box with no
additional software needing to be installed. This is because the Microsoft iSCSI initiator is
built into the operating system.
Windows Server 2012 R2 supports two different ways to initiate an iSCSI session.
■ Through the native Microsoft iSCSI software initiator that resides on Windows Server
2012 R2
■ Using a hardware iSCSI host bus adapter (HBA) that is installed in the computer
Both the Microsoft iSCSI software initiator and iSCSI HBA present an iSCSI qualified
name that identifies the host initiator. When the Microsoft iSCSI software initiator is
used, the CPU utilization may be as much as 30 percent higher than on a computer with a
hardware iSCSI HBA. This is because all of the iSCSI process requests are handled within
the operating system. Using a hardware iSCSI HBA, process requests can be offloaded
to the adapter, thus freeing the CPU overhead associated with the Microsoft iSCSI software
initiator. However, iSCSI HBAs can be expensive, whereas the Microsoft iSCSI software
initiator is free.
It is worthwhile to install the Microsoft iSCSI software initiator and perform load
testing to see how much overhead the computer will have prior to purchasing an iSCSI
HBA or HBAs, depending on the redundancy level. Exercise 1.8 explains how to install and
configure an iSCSI connection.

exeRcISe 1.8

configuring iScSI Storage connection

1. Click the Windows key or Start button in the left-hand corner ➢ Administrative Tools ➢

iSCSI Initiator.

2.

If a dialog box appears, click Yes to start the service.