Bringing iSCSI SAN and Virtualization Together

Sometimes, it takes a few years for a technology to reach mass acceptance in the enterprise space. And to bring powerful tools within the reach of SMBs, you need to add another year or two of product advances and more aggressive pricing. Two technologies that are now reaching broad acceptance—iSCSI SANs and system virtualization—create an opportunity for forward-thinking IT organizations to improve or completely reinvent some long-standing processes involving system provisioning and data protection. Fortunately, both technologies are now within your reach. So, now is the time to learn the ins and outs of implementing iSCSI SANs and virtualization in your Windows environment, and to understand some of the key synergies between SAN and virtualization technologies so that you can implement them to their full advantage.

Why iSCSI?
In a nutshell, iSCSI is a simple, powerful, and effective storage solution for SMBs—without the price tag or learning curve of a Fibre Channel storage architecture. Because iSCSI arrays are connected through standard Ethernet, you can leverage your existing expertise and investment in that technology and take advantage of reasonably priced gigabit-over- copper Ethernet switching (thanks to a higher level of vendor competition than you’ll find among Fibre Channel hardware vendors). As iSCSI vendors target the SMB space, they’re developing tools to simplify the setup, configuration, provisioning, and ongoing management processes for their hardware.

iSCSI SANs offer a range of configurations and features that let IT organizations choose appropriately sized and equipped configurations, and most vendors typically permit relatively seamless expansion through the addition of modular hardware. In addition to traditional RAID configuration support, redundant, hot-swappable components (e.g., disks, control modules, fans, power supplies) can be specified for maximum data availability. Other availability and load-balancing features—such as snapshots, replication, and Microsoft Multi-Path I/O (MPIO)—are available as standard or upgradeable options from most iSCSI SAN vendors.

Most vendors offer solutions that use internal drives connected via Serial Attached SCSI (SAS), Serial ATA (SATA), or a combination of both technologies, giving IT organizations the latitude to tailor the storage environment to specific performance and reliability needs. By nature, SANs are shared storage, meaning that multiple systems can carve out their own piece of the overall capacity. This strategy yields a better utilization ratio than trying to right-size DAS on individual servers. Furthermore, thin provisioning—a storage-virtualization technique that most vendors use—lets you logically allocate more storage space to a volume without fully committing physical storage resources. As the data on the volume grows and more physical storage is actually needed, it’s automatically allocated. The result is more efficient use of your investment in storage.

Why Virtualize?
Virtualization is all about driving down costs and maximizing the utilization of hardware resources. The insanity of adding a server for a single application is only exacerbated by the faster processors and larger memory and disks that ship in today’s standard servers. Virtualization technologies let you run multiple isolated systems on one piece of hardware. Therefore, not only do you get to actually use the CPU cycles available to you, but you also need to buy fewer servers, resulting in less rack space consumed and less reliance on other datacenter resources such as cooling and power.

Virtualization also provides for more flexible and nimble systems management. Because virtual machines (VMs) aren’t tied to a specific piece of hardware, tasks related to provisioning, deployment, and configuration are much simpler and more quickly performed. Backup, maintenance, and migration operations are also simpler, thanks to the nature of a VM’s self-contained, portable system image and emulated hardware description.

Setting Up the Environment
Now, let’s dig into some of the specifics of how to configure these technologies in your environment and see how they can work together. To give this article some hands-on perspective, I built an environment specifically to test some virtualization and disaster-recovery scenarios. For my iSCSI SAN, I used a Dell EqualLogic PS5000X storage array and I installed both Microsoft Virtual Server 2005 R2 SP1 and VMware ESX Server 3.5 to create a combination of virtual server and client systems.

Installing and configuring the iSCSI array. Installation of the EqualLogic iSCSI array was pretty simple, thanks to the Host Integration Tools provided on an included CD-ROM. If you’ll be using Microsoft Storage Manager for SANs (SMfS)—a simple storage- management tool available in Windows 2003 R2 and later—you’ll want to ensure that your storage vendor provides a Virtual Disk Service (VDS) hardware provider, which is essentially an interface between the storage system and the Microsoft VDS. In my tests, the EqualLogic tools’ installation process detected the SMfS installation and automatically installed its VDS hardware provider. I used the vendor-provided tools to initialize the storage array, configure a storage group, and set my server’s iSCSI configuration to access the SAN. I used the Web-based SANTest Group Manager tool, which Figure 1 shows, to provision an initial volume and perform basic SAN monitoring and management tasks throughout my usage of the storage system. It took about an hour to get the array configured and ready to manage through SMfS.

Systems that will connect to an iSCSI resource need to have a dedicated NIC or an iSCSI host bus adaptor (HBA) card specifically for connecting to iSCSI storage. There are a few advantages to using an HBA instead of a standard NIC, including performance and a simpler boot-from-SAN configuration, but for my testing I used standard gigabit-over-copper NICs from Intel and Broadcom. Also, you need to give some consideration to the network infrastructure over which your iSCSI traffic will travel. You should employ enterprise-class, nonblocking gigabit-over-copper Ethernet switches. If you don’t want to (or can’t afford to) maintain a completely separate network environment for your iSCSI devices, you should at least use a Virtual LAN (VLAN) for the ports through which iSCSI traffic flows.

Setting up the virtualization platforms. When you’re considering a virtualization tool, you have a few vendor choices, and those vendors typically offer multiple platform choices and management tools. To keep things simple, I’ll stick to Microsoft and VMware’s popular virtualization products. Setting up the virtualization platforms for my tests was relatively easy. I downloaded Virtual Server 2005 R2 (see the Learning Path at InstantDoc ID 99229 for download details) and followed the simple installation instructions to set it up on two Windows Server 2003 R2 systems. After the installation, an information page outlined how to access the Virtual Server Administration Web site. The management interface is intuitive, and the process of creating and provisioning new systems is straightforward.

I downloaded an evaluation version of VMware Infrastructure 3, which contains ESX Server 3.5 (for download details, see the Learning Path) and created an installation CD-ROM from the ISO image. Unlike the Microsoft virtualization software, ESX Server doesn’t run on top of Windows Server. I booted from the installation media and had the ESX Server system running in about 30 minutes. To manage the ESX Server system, I could either install the VMware Infrastructure Client or use the Web-based client.

At this point, both virtualization platforms were ready to create and provision new VMs on local disk volumes. To leverage the iSCSI SAN, I needed to prepare and connect SAN volumes to the Virtual Server and ESX Server systems. For more information about configuring SAN storage on Windows and VMware platforms, see the Web-exclusive sidebars “Configuring SAN Volumes for Windows Virtual Server” (www.windowsitpro.com, InstantDoc ID 99231) and “Configuring SAN Volumes for VMware ESX Server” (InstantDoc ID 99232). And remember that an essential part of any VM strategy is backup. The Web-exclusive sidebar “Backing Up Virtual Systems” (InstantDoc ID 99254) discusses recommended practices.

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