ljplicease | xen and the art of rackspace

I have been trying to find the time and the resources to get a xen testbed up and working because my hosting company, Rackspace (and before that Slicehost) used xen to power their cloud servers and I thought it would be worth having some experience in that area since I currently depend on it, and even if I do switch providers I will likely be looking for one that provides a xen based solution. My first attempt was when I got a new CPU server/workstation recently. Unfortunately I discovered that xen and Nvidia don't play nice together so I wound up using KVM instead. I am actually glad, because KVM is more flexible and makes possible, if not always easy, to migrate from VMware. There is a definite performance advantage to xen, because the guest and host kernels cooperate.

Anyway, I finally was able to repurpose my old CentOS/VMware server as a Debian/Xen server I started hacking around. I noticed the disk devices in the xen VMs that I created were using /dev/xvda instead of the usual /dev/sda, even though I seemed to remember that on Rackspace (and before that Slicehost) the devices are /dev/sda. I took a look at the MAJOR and MINOR codes on the devices in my xen VMs and the ones on the Rackspace VM, and sure enough, the Rackspace VMs are using /dev/xvda too, they have just changed the name, presumably because that is what people are used to seeing. Next out of curiosity, I tried to fdisk /dev/sda on the Rackspace VM, only it isn't there. When I created it using mknod and tried to fdisk it again I got a permission error. I am sure this is a security thing and I wasn't really worried about it, but I tweeted something about it as a sort of joke. Rackspace responded:

@plicease Could you email details to us? We'll help you figure out what it is. twitter @Rackspace .com

I hadn't put Rackspace in a # or used @ to refer to them or anything I guess they just troll the Interwebs for any mention of them in a sort of proactive tech support? They have always claimed to have fanatical tech support. Is this fanatical though, or maybe a bit creepy? Twitter is a public forum, and I post my tweets publicly so I can't really complain.

For the most part, they have always been quite good, although I have to say they seem to be a wee bit better when I had a dedicated server with them than they are now when I have VMs (there was a period for a number of years between those two scenarios when I had different hosting companies). Bad hardware has caused two of my VMs to go down on two separate occasions occasions (one VM each time). That sort of thing happens from time to time, and I'm not really complaining but over a much longer period, I never had a fault with my dedicated server.