Virtualization hides differences in hardware

* Another benefit of server virtualization

One possible use of virtualization technology is as a hardware-abstraction-layer to hide the differences between servers in a data center.

Even if you buy servers in batches of hundreds of thousands, you are almost guaranteed to get slight variations in the underlying hardware. Even within the same brand and model, there will be differences in chipsets and firmware, forcing system engineers to configure each system differently. All the slight configuration variances between servers make management and operations more costly. These hardware differences may even cause uncertainty in the behavior of the application.

In the average data center, of course, you do not often see racks of identical servers, nor are servers bought in batches of thousands. As the data center grows organically, multiple brands, models, configurations (e.g., single- or dual-CPU) are the norm.

This is a challenging environment for system administrators and application developers. System administrators must manage dozens of disparate operating system configurations, with different drivers, versions, updates and patches. Application developers may find discrepancies between the testing and production environments that cause unforeseen problems in the application.

Virtualization or hypervisor software hides the differences between servers to present a standardized generic set of virtual devices to the operating system running inside the virtual machines. As far as the operating system is concerned, it is running on whatever hardware device the virtual machine is emulating. The virtualization software is responsible for translating between the fake devices and the actual devices found on the physical server. Although system administrators still must configure the virtualization software to account for small differences in the server hardware, they no longer need to apply different configurations to the operating system within. Thus, operating system management is greatly simplified. Administrators can store a single operating system “image,” configured with the virtual machine as its “target” platform, on the SAN or NAS. Similarly, application developers can test their applications on the virtual machine platform with the confidence that they will be using an identical configuration in production regardless of the underlying hardware. If they need to move an application needs to a different server temporarily, say for maintenance of the physical server, they can do so without concern about incompatibilities between servers.

Nemertes Research provides additional analysis of the risk and maturity of virtualization-based solutions as part of the Data Center benchmark report.

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Copyright © 2006 IDG Communications, Inc.

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