Tuesday, April 17, 2007

Another Round with the Laptop

Having recently switched a bunch of older Fedora Core servers to CentOS 4, I became very excited to see the announcement that CentOS 5 has been released. I am very pleased with the polish and stability of CentOS 4 and thought 5 would be a perfect update for my (then) Ubuntu laptop. My laptop is a fairly old IBM Thinkpad T23 - certainly not bleeding edge hardware.

The display was maxed out at 800x600 rather than the native 1400x1050 I'm accustomed to and my NetGear wifi card was recognized, but not functional. It comes as no surprise that none of my Thinkpad buttons worked. I spent the past 10 years of my hacking career tweaking Linux boxes, and I was using X windows in the days when you actually risked toasting your monitor with a bad config. So, yes, I could make X work. And I have gone through the Windows wifi card firmware dance, so yes, I could make the Wifi card work as well. I could also recompile the kernel and add Thinkpad buttons and ACPI events. Yuck. My rebuild just turned into a lot of research and work.

On a whim I thought I'd try Fedora Core 6 just in case my problems stemmed from the more conservative approach CentOS takes. Same problems, although I love the eye candy in Fedora - their art is great.

I didn't bother to try Solaris x86 because I know it won't detect any of my special hardware. Someday I'd love to be able to use Solaris outside of work, but that day hasn't come yet on the desktop.

So here I am, back with Ubuntu. It detects everything and works right out of the box. Within an hour I had a fully functional laptop, and despite my 1 GHz CPU in a 5GHz world it performs great. I suppose a year from now I'll try it again since I prefer a Red Hat based distribution to a Debian base. But what matters most comes down to two words: "It Works."

Thanks, Ubuntu.

Sunday, April 01, 2007

Does Your Virualization Strategy Have a Blind Spot?

I just finished reading a very interesting article about virtualization. It described the test results of running two sample web applications under virtual and physical environments. The idea was simply to check how the virtualization affected the application's performance. The results are interesting.

Before I go further, let's clarify that this article is about Windows IIS and Win2k3 server, so it is not about Solaris, or any other flavor UNIX beyond the fact that the underlying OS for VMWare in this case was CentOS. None the less I believe the story's moral is highly applicable to any operating environment, definitely including UNIX.

There is a lot of detail in the article, but if we can assume their methodology to be relevant, we can reduce it down to a short extract from its conclusion: "a virtualized server running a typical web application may experience a 43% loss of total capacity when compared to a native server running on equivalent hardware."


Of course, I have no reason to think that this function carries over directly to Zones, Xen, or even VMWare running Linux. To believe this without research would be to abandon one's Jedi training. It would be a very valuable experiment to try such an excercise though, because I have no reason (at this moment) to think it would not have some relevance.

The big point here I want to make is that I would bet there are a great many sites out there who dilligently track low hanging fruit metrics like CPU utilization, and use that metric both in planning and asessing their virtualization projects. Server "A" runs an application and on average sits at 10% utilization. Lets call it 100Mhz and find it a home on the consolidation farm. Not so fast.

The problem is that if you completely ignore business metrics, you will fail to identify this article's identified flaw in virtualization. Hey, we moved from 8 servers down to one, and its at 80% all the time. Success! But what if that new server is running at 80% and only processing 50% of the volume it used to? I would suggest that the article I referenced might be a great reason to reflect on your site's metric stratgey and see if you have the ability to accurately asess a consolidaton stratgy. If not, you could be making an expensive transition.