The Case for Virtualization on Blades

Last month, the debate over blade servers in “large-scale” virtualization and consolidation projects heated up as Rod Lucero, CTO of the VMware consultancy VMPowered, said he would not recommend using blade servers in such situations. While our focus here is PC Blades, we think it’s important to follow up on Mr. Lucero’s comments and to take a look at the other side of the debate:

“The big problem with blades, Lucero said, is the limited number of network interface cards (NICs) you can attach to a blade – ‘two, and that’s it,’ he said, although some newer blade systems are starting to support more … Lucero’s other gripe with blades is that they are often sold diskless, thus requiring the blades to boot from SAN – a less-than-perfect process.” (Server Virtualization News)

Lucero implies that blades will by default be fully loaded with highly dense configurations, but this doesn’t always have to be the case. ClearCube’s proposed blade virtualization is targeted at Virtual Desktop Infrastructure (VDI), which pushes desktops into virtual desktops in the datacenter. By using a PC Blade to support VDI the installation is less dense and as a result there is no performance threshold problem with I/O. In fact, I/O is the least stressed component of the whole system. It is not always necessary to go to 10 GB networking to support a VDI configuration.

However, when 10 GB is necessary, blades can handle that as well:

“BLADE Network Technologies and NetXen have teamed up to provide 10 Gigabit Ethernet connectivity for IBM BladeCenter systems. In a bid to both extend the market for blade systems and take 10 Gigabit Ethernet blade systems mainstream, the companies are anticipating strong demand for 10 Gigabit Ethernet blade servers for virtualization and High Performance Computing…” (VM Blog)

As to the boot-from-SAN complaint, Blade Watch’s Martin MacLeod sums it up well: “Sure SAN booting can be complicated and needs to be done properly, but when it’s configured correctly, the results energy wise and thermally can be significant.”

As energy efficiency and space issues grow in importance, businesses will be hard pressed to ignore the advantages of blades over traditional desktops and rack-mounted servers. So, despite the debate, neither blades nor virtualization are going away:

“In 2010, close to 15% of the new servers shipped will be virtualized, versus just 4.5% of the new servers shipped in 2005, according to IDC … Though blade servers accounted for only about 7% of the roughly seven million servers shipped in 2005, IDC estimates, that percentage is projected to swell to 26% by the end of the decade. That’s a fivefold jump in unit sales, compared with a projected 33% increase over the same period for conventional servers.” (Bob Michaelian)