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While the benefits of server virtualization at the corporate data center are receiving a great deal of attention, its ability to address lifecycle management issues may make virtualization even more compelling at the manufacturing plant. Along with the advantages, however, come additional challenges and risks. This paper offers best practices you can use to benefit from server virtualization today, while avoiding mistakes that could affect the availability and performance of mission-critical manufacturing IT.
Server Virtualization for the Plant
Many companies are eager to jump into server virtualization, the practice of using a software layer to let one physical computing server run multiple virtual machines. Among many other advantages, server virtualization allows companies to save money by consolidating a number of applications on the same physical server.
Virtualization is a time-honored approach in the mainframe world, but its growing use today involves virtualization on x86 servers. The current surge of virtualization in the enterprise began with applications deemed less critical, characterized by lower processing requirements and tolerant of limited service outages.
Implementing virtualization in manufacturing environments moves the technology into the mission-critical realm. Manufacturing Execution Systems (MES) and related automation applications can gain advantages from virtualization that go beyond even those seen in typical enterprise software applications _ although special concerns apply as well.
Why Manufacturing is Mission-Critical
Manufacturers are adopting new IT solutions on an unprecedented scale to meet efficiency, quality, and regulatory compliance goals. And any time that you rely on complex integrated IT solutions in production environments, service interruptions quickly become unacceptable.
In applications such as MES, for example, unplanned downtime results in lost production time. In regulated industries like pharmaceuticals, loss of data and/or control can comprise the integrity of a batch record and require in-process product to be destroyed. Even minor system interruptions can call into question the value of the IT solution.
While application consolidation has many significant benefits for MES, significant risks exist when the underlying platform (including hardware, virtualization software layer, and drivers) is not sufficiently robust. Platform faults could cause a facility-wide outage, and worse, long recovery time.
Using server clustering to provide a robust platform presents another challenge. Running a single application clustered on multiple servers in a non-virtualized environment is difficult enough. With virtualization, IT personnel have to deal with the complexity of configuring, testing, and maintaining multiple applications that are clustered on the same platform.
Therefore, evaluating and addressing an application’s availability requirements is an important consideration before moving to a virtual environment. Before exploring these and other concerns in more depth, let’s first review the basic concepts of server virtualization.
Server Virtualization Basics
In a virtualized environment, each virtual machine on a physical server exists within its own container or partition. While implementations differ, generally speaking each partition contains an application (or applications) and an instance of an operating system known as a guest operating system (OS).
A number of these partitions sit on a software layer called a hypervisor. The hypervisor is the thin, low-overhead layer that manages the basic services necessary to host the applications and their guest operating systems.
Each virtual machine runs a separate instance of an operating system and application(s), and has access to a portion of the server’s resources.
The virtual machines on a server may use the same flavor of operating system, use different releases of the OS, or use entirely different types (e.g., Windows® and Linux®) of operating systems.
Some approaches use a host operating system below the hypervisor, but these impose system overhead. More recent solutions promote “bare metal” performance, which becomes possible when the hypervisor is implemented directly on the server hardware.
The market offers a number of commercially available software-based server virtualization products. The trend is to support virtualization that includes both Windows and Linux operating systems. VMware holds the largest market share. XenSource has introduced the concept of open-source virtualization. Microsoft likewise provides solutions for the Windows OS, and is working to extend support to the Linux OS. In addition, these vendors have announced initiatives that would allow their virtualization solutions to work together, which holds promise for standardization.
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