Blades vs. Virtual

Well – I started conceiving this as a definitive “Blades vs VMWare” post.  I was fully expecting that by the end of the week I was going to have enough information about bladeservers, and the IBM BladeCenter in particular to be able to say one way or another.

I’m here to report that I’ve failed to come to any conclusion whatsoever.

Blades seem to have some advantages, the most obvious being the ability to shut down one node for a hardware problem or upgrade rather than having to take multiple VM hosts offline.  But then VM also holds several major advantages, flexibility, scalibility, etc.

Here are the pros/cons I’ve found:



  • Individual servers can be removed and replaced for hardware issues.
  • Hardware clock (I’ve had issues with clock-drift on VMWare systems)
  • Actual service console.


  • Power Consumption – a blade takes almost as much power to run as a standard server.
  • Cooling (The fans on the back of a single bladecenter blow HOT air at 90 miles an hour)
  • System utilization – a Blade has the same limitations as a PC, if it’s not utilized effectively, 70-90% of the processor can sit idle.



  • Much smaller footprint – on a powerful enough server, 7-10 VM’s can reside on a single 2U server.
  • Power Consumption – A fully utilized Dell 2950 can run 8-10 VMWare systems with minimal increase in power consumption.
  • Cooling – see above
  • Management – Because of the virtual console, a VMWare system can be managed remotely much more easily than a blade-based system can.


  • Clock Drift- as I’ve said, I’ve had a recurring problem with clock-drift that not even the VMWare tools can compensate for.  I think right now the system I have running this website is 13 hours ahead.  This will be corrected on the reboot, but it doesn’t seem that the VMWare clock syncs with the hardware clock in the Dell at all.
  • Management – obviously I’ve had some VMWare experience, and I manage my own stuff.  However for corporate users, someone will have to be trained and gain some experience before you can really be proficient at managing a VMWare environment.  Small misteps can bring down entire environments if you don’t know what you’re looking for.

Trust me – I know. 🙂


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