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7. On the Confirm Installation Selections page, verify that Multipath I/O is the feature that will be installed. Click Install.
8. After the installation completes, the Installation Results page appears stating that the server must be rebooted to finish the installation process.
9. Click Close.
10. Restart the system.
Typically, most storage arrays work with the Microsoft DSM. However, some hardware vendors require DSM software that is specific to their products. Third-party DSM software is installed through the MPIO utility as follows:
1. Open Administrative Tools ➢ MPIO.
2. Select the DSM Install tab (see Figure 1.7).
FIGURE 1.7 The DSM Install tab in the MPIO Properties dialog box
3. Add the path of the INF file and click Install.
iSCSI
Internet Small Computer System Interface (iSCSI) is an interconnect protocol used to establish and manage a connection between a computer (initiator) and a storage device (target). It does this by using a connection through TCP port 3260, which allows it to be used over a LAN, a WAN, or the Internet. Each initiator is identified by its iSCSI Qualified Name (iqn), and it is used to establish its connection to an iSCSI target.
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.
3. Click the Discovery tab.
4. In the Target Portals portion of the page, click Discover Portal.
5. Enter the IP address of the target portal and click OK.
6. The IP address of the target portal appears in the Target Portals box.
7. Click OK.
To use the storage that has now been presented to the server, you must create a volume on it and format the space. Refer to Exercise 1.3 to review this process.
Internet Storage Name Service
Internet Storage Name Service (iSNS) allows for central registration of an iSCSI environment because it automatically discovers available targets on the network. The purpose of iSNS is to help find available targets on a large iSCSI network.
The Microsoft iSCSI initiator includes an iSNS client that is used to register with the iSNS. The iSNS feature maintains a database of clients that it has registered either through DCHP discovery or through manual registration. iSNS DHCP is available after the installation of the service, and it is used to allow iSNS clients to discover the location of the iSNS. However, if iSNS DHCP is not configured, iSNS clients must be registered manually with the iscsicli command.
To execute the command, launch a command prompt on a computer hosting the Microsoft iSCSI and type iscsicli addisnsserver server_name, where server_name is the name of the computer hosting iSNS. Exercise 1.9 walks you through the steps required to install the iSNS feature on Windows Server 2012 R2, and then it explains the different tabs in iSNS.
EXERCISE 1.9: Installing the iSNS Feature on Windows Server 2012 R2
1. Choose Server Manager by clicking the Server Manager icon on the Taskbar.
2. Click number 2 ➢ Add Roles And Features.
3. Choose role-based or featured-based installation and click Next.
4. Choose your server and click Next.
5. Click Next on the Roles screen.
6. On the Select Features screen, choose the iSNS Server Service check box. Click Next.
7. On the Confirmation screen, click the Install button.
8. Click the Close button. Close Server Manager and reboot.
9. Log in and open the iSNS server under Administrative Tools.
10. Click the General tab. This tab displays the list of registered initiators and targets. In addition to their iSCSI qualified name, it lists storage node type (Target or Initiator), alias string, and entity identifier (the Fully Qualified Domain Name [FQDN] of the machine hosting the iSNS client).
11. Click the Discovery Domains tab. The purpose of Discovery Domains is to provide a way to separate and group nodes. This is similar to zoning in Fibre Channel. The following options are available on the Discovery Domains tab:
■ Create is used to create a new discovery domain.
■ Refresh is used to repopulate the Discovery Domain drop-down list.
■ Delete is used to delete the currently selected discovery domain.
■ Add is used to add nodes that are already registered in iSNS to the currently selected discovery domain.
■ Add New is used to add nodes by entering the iSCSI Qualified Name (iQN) of the node.