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Closer to home, in a survey of Storage magazine readers last month, a whopping 80.3% indicated that they were using, evaluating or planning to evaluate some form of virtual server technology. (See "
What do virtual machines have to do with storage? Quite a bit, as many early adopters have discovered. The kind of storage you use can impact the overall success of your virtual server environment. Conversely, virtual servers can help ease your storage management burden, and help you get more out of existing storage resources. They also can simplify disaster recovery greatly. But until storage management software catches up to the virtual server world, you may face some obstacles with routine storage management tasks.
Virtual servers--or virtual machines--are not new. Originally developed for the mainframe, the technology is essentially a way to abstract a server's physical compute and I/O resources, and run several operating systems at the same time. Thus, a single physical server, instead of running a single instance of an operating system, runs a control function on which you load multiple "guest" operating systems. With virtual machines, you can consolidate several small physical servers into a single large server, reducing the number of machines--and operating system licenses--you need to buy, install and maintain. With virtual machine technology, it's also quicker to deploy a new server, a boon for test and development environments or data centers that grapple with dynamic, fluctuating workloads.
Virtual machine capabilities are available in some form or other for all the major server platforms: Logical Partitioning (LPAR) for IBM Corp.'s iSeries and pSeries servers; Sun Microsystems' Dynamic System Domains; and Hewlett-Packard Co. (HP) with vPAR for HP-UX. On the Intel Corp.'s x86 platform, VMware leads the pack. The technology's appeal lies in improving management, reducing server footprint and maximizing resources. "It's a consolidation play, and it's wildly popular," says John Webster, founder and senior analyst at Data Mobility Group, an analyst firm in Nashua, NH.
It's no surprise therefore, to find that many of the vendors promoting virtual server technology have certified configurations that include storage area network (SAN) technology. For example, among its virtual server offerings, Dell Computer Corp. sells a four-processor PowerEdge 6650 server with VMware's ESX Server and a Dell/EMC Clariion SAN. "It's not a requirement, but the marriage of the two makes a lot of sense," says Subo Guha, Dell's director of software product marketing. "It provides for the growth and allows them to consolidate their storage data."
One joint Dell/VMware customer is Oak Associates, a financial services firm in Akron, OH. Last year, the firm embarked on a server migration project, moving away from its aging HP/Compaq DL380s to two-processor Dell 2650s. Of the firm's 110 servers, 80 are virtual machines, with an average of eight virtual machines per physical server.
Oak Associates is running a combination of VMware's GSX Server, which runs on a Windows kernel, and the higher-performing ESX Server, which provides its own Linux-based kernel across 16 servers, with an average of eight virtual machines per physical host. On them, Oak Hill runs Microsoft Windows and a variety of applications, ranging from the company's accounting software to DHCP and domain controllers. In fact, the only applications not hosted by VMware are those that need all the CPU power they can get, such as Microsoft Exchange, says Scott Hill, senior technology officer with the firm.
This was first published in July 2004