Redmond giant's foray into server consolidation.
In our Clear Choice Test, Virtual Server 2005 proved itself well worth the money because it lets you run multiple instances of Windows on the same machine.
In our Clear Choice Test, Virtual Server 2005 – technology Microsoft picked up with its 2003 Connectix purchase – proved itself well worth the money ($495 for a host with up to four CPUs) because it lets you run multiple instances of Windows (NT 4.0 with Service Pack 6 on up to 2003) on the same machine. And with the Virtual Server Migration Kit, it provides a way to gracefully move and consolidate older Windows NT and 2000 Server applications onto new (and ostensibly higher-capacity) hardware. The migration kit also helps resolve Windows-specific hardware issues, such as migrating a Windows 2000 server running on an ancient SCSI host bus adapter to new storage subsystems inside the host machine with very little modification.
How we did it
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VMware (recently acquired by EMC) has long offered server virtualization with its ESX and GSX Server wares for a variety of operating systems . Virtual Server 2005 is not as elegant as VMware’s software and only officially supports Windows servers.
Virtual Server 2005 runs as a Windows service on a Windows 2003 Enterprise Server box. An administrator then can establish multiple concurrent server environments – called virtual machines – on that single physical server, each with its own limitations in terms of what resources it can access. We suggest multiple CPUs for the hardware and a great deal of RAM (a minimum of 512M bytes per virtualized server plus another 512M bytes as a base).
We easily installed Virtual Server 2005 on three hardware platforms: a dual-CPU NFrame 1600, a dual-CPU HP DL380 and a four-processor HP DL580 (see “How we did it” ).
The Virtual Server 2005 Management Console is a Web-based program, and its real estate is somewhat ugly and poorly managed. Although, the ability to monitor each of the virtualized servers via a Web page simplifies that process a great deal.
There are three ways to build a virtual machine inside a host server. The first is to install the server software onto an allocated virtual machine, which when booted appears as though it is a new server. The second method is to copy resource settings from another already-built virtual machine. These settings, along with loaded application, can be easily replicated to create additional virtual machines. The third way is to migrate a compatible server/application instance to a virtual machine using the migration kit.
After installing Virtual Server 2005, you can either use Microsoft’s preset parameters or tap into the GUI to establish your own settings for each virtual machine. Those settings include disk control (size, type of disk, location and allocated space), maximum memory to be used, IP address and operation mode. Each virtual machine can be named and can use network addresses that are internal, external or on a virtual network. These virtual machines also can stand alone and not be connected to a network.
The virtual machines lock host resources – such as CD/DVD players, serial ports, parallel ports and other devices – when they use them so that other virtual machines cannot access those host resources. Other resources may or may not need to be used sequentially. As an example, disk drives can use either shared or privately allocated space but never the same files except as read-only resources. Certain resources such as external USB drives, authentication token or biometric authentication devices cannot be shared devices.
In our tests, we generated and then migrated several server types. The total migration time ranged from just under six hours for MS SQL Server running on NT 4 SP 6 to just more than seven hours for Microsoft Exchange 5.5 running on Windows 2000 Advanced Server SP 3. These measurements include the time it took to build the images, resolve resource settings, install the image onto the virtual server, and restart the server and its applications. Faster hardware certainly helps speed the process, as does close reading of the detailed migration kit documentation.
The migration application and scripts successfully remapped hardware resources. The software also let us remap the Ethernet card media access control address of old cards to new server addresses.
When we deployed Virtual Server 2005 on a four-way HP box, our test was designed to stress capacity and availability levels under crash conditions. We built eight virtual machine running Windows 2000 Server to run concurrently in a minimal amount of memory (128M bytes each) space. We then ran SSL logons against each virtual machine until allocated CPU was saturated for each. We found that each virtual machine behaved according to our desired resource parameters. We then tested disk I/O contention and found multiple concurrent writes to disk could quickly pile up the cache on each virtual machine, but we could spawn no errors through normal use.
Other tests known to generate a blue screen/crash affected only the crashed individual virtual machine we targeted and the resources we allocated to it, rather than destabilizing the entire Virtual Server 2005 platform.
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We noted that to reach this level of stability, we had to upgrade our host server to Win 2003 Enterprise Server SP 1.
When we purposely crashed a virtual machine, its high CPU utilization might have gone unforeseen if we had not also used the Microsoft Operations Manager (MOM) 2005 with appropriate management packs for Virtual Server. Without MOM 2005, you must view a console or monitor system logs to find that sessions have gone haywire.
We found that disk speed in a virtual machine stood within 5% of its speed on its native host platform on all servers tested. CPU performance using rudimentary tests was often as fast as the host, but could be bogged down by high disk I/O.
Overall, we found Virtual Server 2005 to be a strong virtual machine platform. The stability of the product shows the legacy of the Connectix technology, even if the user interface not as pretty as we’d like.
