Xen masters take aim at VMware

It seems all roads lead to virtualization these days. From every conceivable angle, computing resources are being collapsed into abstraction layers that enable greater flexibility, and storage, application, server, and desktop virtualization vendors are riding the wave. The biggest push and most appealing opportunity is server virtualization, and the biggest and most appealing vendor is VMware. VMware isn't just the biggest player, however; it's also the most expensive option.

The market that Virtual Iron and XenSource are currently targeting is the low-to-middle end of the spectrum. Its offerings boast most of the features of VMware's flagship products without the hefty price tag. After working with both virtualization platforms for the past few weeks, I can report that these vendors are well on their way, but rough edges abound.

VMware's head start over the rest of the market is substantial. Leveraging nearly a decade of experience and development, VMware Infrastructure 3 has proven to be a very stable, high-performance platform, with wide OS and hardware support and a very clean and functional set of management tools in VirtualCenter (read my December 2006 review). Virtual Iron and XenSource are relative newcomers to the virtualization scene, the duo leveraging the open source Xen hypervisor. Although Xen is the core of both, the Virtual Iron and XenSource products are very different in form and function, not to mention design.

I tested the two platforms on Dell PowerEdge 2950s with dual dual-core 3GHz Intel Xeon 5160 CPUs and 4GB of RAM, using a NetApp StoreVault S500 as the iSCSI back end and Cisco gigabit copper switches in the middle. The NICs in the machines were built-in Gigabit Ethernet, with the addition of another Intel NIC to provide the three-NIC layout required by Virtual Iron when using iSCSI. A low-cost multidialect filer, the NetApp StoreVault fits with the budget-conscious theme of both XenSource XenEnterprise and Virtual Iron Enterprise.

Virtual Iron Enterprise Edition

Virtual Iron's take on virtualization is different from nearly every other vendor. The basis of its enterprise product is a dedicated management server and a bevy of potentially diskless processing nodes. The installation of Virtual Iron 3.7.1 is very straightforward. After building a server with Red Hat Enterprise Linux 4, Suse Linux Enterprise Server 9 SP3, CentOS 4.4, or Windows Server 2003, installing Virtual Iron is as simple as double-clicking an icon.

There are certain prerequisites for the management server, however, most specifically that it have several network interfaces and that those interfaces be connected to specific network segments. The front-end interface is used to provide access to the management tools, and the back-end interface is used to boot servers that will be handling the virtual machines. This split design is quite elegant, and it provides a mechanism for extremely fast deployment of new host servers into the mix. Once the management server is built and running, adding new compute servers is generally as simple as turning them on and configuring them to PXE (Preboot Execution Environment) boot from the NIC connected to the back-end network. The downside of this approach is that you lose a NIC on each server, possibly requiring the installation of at least one more NIC in each server, and probably several more NICs if iSCSI storage will be used.