Religious Issue #7: Racks or Blades?
One of the most contentious issues that can come up in virtualization circles is the debate on whether to use blades or chassis servers for virtualization hosts. The use of blades did come up in a recent
Virtumania podcast discussion. While I've worked with blades over the years, most of my virtualization practice has been with rack-mount chassis servers.
After discussing blades with a good mix of experts, I can say that blades are not for everybody and that my concerns are not unique. Blades have a marginally higher cost of entry, meaning that up to six blades are required to make the hardware purchase more attractive than the same number of chassis servers. The other concern that I've always had with blades is effectively shrinking a domain of failure to include another component, the blade chassis. Lastly, I don't find myself space-constrained; so why would I use blades?
Yet, it turns out that blades are advancing quite well with today's infrastructure. In fact, they're progressing more swiftly than my beloved rack-mount chassis server. Today's blades offer superior management and provisioning, ultra-fast interconnects and features on-par with CPU and memory requirements of the full server counterparts. A common interconnect between blades is 10 Gigabit Ethernet, which, in virtualization circles, will lead the way for ultra-fast virtual machine migrations and can make Ethernet storage protocols more attractive.
So, why not just go for blades? Well, that just depends. Too many times, other infrastructure components are in different phases of their lifecycles. The biggest culprit right now is 10 Gigabit Ethernet. I think that once this networking technology becomes more affordable, we'll see the biggest obstacle removed for blades. Cisco's Unified Computing System requires a 10 Gigabit uplink, for example. Blades can also allow administrators to take advantage of additional orchestration components that are not available on traditional servers. The Hitachi Data Systems Unified Compute Platform blade infrastructure allows the blades to be pooled together to function as one logical symmetric multiprocessing server.
Blades bring the features; that is for sure. Which platform do you use, and why? Are you considering changing to blades? Share your comments here.
Posted by Rick Vanover on 08/03/2010 at 3:27 PM