Back with a Xengence

I’ve recently come into possession of 2 fine Dell 2950 servers and I’ve been trying to figure out how I want to configure them.  I had them sent to me without any O/S on them, so as to make the decision a bit harder :-)

What I’d like to do is split each machine into 2 virtual machine “containers” that I can run a variety of images / configurations in.  I played around with using VMWare ESX Server, but balked a bit at the price of the management server.  After that I started to look into the Xen software.  Basically it started to come down to whether or not I wanted to boot into a thin hypervisor, or run a straight O/S “underneath” the hypervisor.

I decided to run Linux underneath any hypervisor — so at that point it came down to which Linux to run.  I see a lot of raves for Ubuntu and CentOS on the blogs, but in the end I decided to give Oracle’s Unbreakable Linux a whirl.  I downloaded  the 5 ISO’s, “remembered” how to burn ISOs to CDs and then booted the Dell’s using the CDs — worked like a champ.

And, lo and behold, Xen was included in the distro — no need to install it.

So began my fun with Xen.

The first challenge I had was trying to get an O/S installed into the Virtual Machine I created.  There’s a graphical Virtual Machine “manager”, but it’s not much more than a wrapper around the base Xen (xm) commands.  I find this to be a pain with all of the virtualization managers — guest O/S installation.  The installer asks me for a URL or FTP of the ISO images — and since I’ve just configured these 2 machines from scratch, I don’t have that stuff set up.  What I have is the 5 CDs — I want to use them.  (Actually, I would just like it to clone the installation I’ve just done — I don’t want to install the O/S again — just use the same one I already have).

I try using the CDs and have all kinds of fun.

First problem is the graphical console to the VM — the mouse position appears “relative” — I can’t navigate to certain areas of the virtual screen.  This is a “known” issue, so I give up on the graphical installer and use the text mode.  Everything is fine and dandy until it asks me for the 2nd CD.  I push the eject button on the drive and nothing happens.  Here’s where I learn about how the CD drive is managed between the host O/S and the various VMs.  I can understand the challenge here — you need some way to attach the drive to a specific VM and manage conflicting access demands.  I get close using the block-detach force and block-attach commands — I get the 2nd CD mounted, but I run out of luck on the 3rd CD — no idea why.  What I really want is a DVD install disk instead of the 5 CD images.  I’ve got a DVD burner in my laptop — should be a piece of cake — just locate the DVD ISO…..  Not a lot of luck there either.

I finally find this (Create RedHat DVD from CD ISO Images) which gets me 99% of what I need instructions-wise.  Once I get my DVD ISO and burn it — I’m on my way.  One minor thing — I needed to go into the BIOS and enable CPU Virtualization support (why isn’t it on by default? — some other issue?).  Once that’s done, I get my VMs up and running.

One other odd thing — when you shutdown a Xen VM there isn’t an obvious way to restart it — it disappears from the graphical manager.  Actually, you “re-create” it, re-using the configuration file from when you “created” it in the first place.  So, xm create sherman will actually restart the sherman VM if it has a valid config file in /etc/xen.  Seems odd to me as “create” implies “create from scratch”.  Now with sherman and mcpherson running on top of the grant domain0 my next task is to add disk space to them….

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