XenServer: A sneak peek
Posted on October 13th, 2010
So for the last little while, you’ve probably heard Zak and myself (Ryan) talk about a new virtualization platform that we at SevenL are rather excited to be moving to very soon…You’re probably wondering when it’s happening, and I can only say, “Soon.” Why? Well, simply because this new platform is quite possibly the most advanced of its kind…to a point where, in my opinion, it really is in a class all its own.
Enough of the sales pitch though, I’m writing this because many of you out there are just as geeky and tech savvy as we are, and I want you all to understand why it is we here at SevenL are going so completely bonkers over the possibilities this new platform brings…so, without further ado…madames et monsieurs, damen und herren, laaaaaaaaaaaaaaaaadiiiiiiiiiess annnnnndddd gentlemeeeeennnn….in this corner, weighing in at a little under 2 gigabytes….XENServer!
XenServer is a platform developed by Citrix that is based on Xen…yes, the very same Xen we started off here years ago using as our ORIGINAL virtualization platform…but here’s the thing, XenServer is to Xen, what an F-22 Raptor is to a crop duster. XenServer is, at its core, still similar to its purely open source cousin, but so much has been built on top that you could more likely call it a DISTANT cousin to Xen. So, what’s in the box?? Well, let me take you through some of the finer points of what is possibly the most advanced virtualization platform I know of.
Dynamic resource control: XenServer guests (or domUs, if you want to get all technical) can, on a moment’s notice, change core resources like VCPU and RAM allocation WHILE THE GUEST IS RUNNING.
XenMotion: Seasoned VMWare vets know all about vMotion…and this is sort of Citrix’s offering to that effect. For those knew to virtualization or VMWare and XenServer, XenMotion is a critical part of XenServer’s High Availability infrastructure that allows guests to be migrated with absolute zero downtime. Put simply, we can migrate your VPS to a new host machine, and you won’t even know its happening.
Rapid Provisioning: Because of how XenServer is implemented at the OS level, we can have guests up and running in seconds, not minutes (depending on the scenario).
Built on Linux: XenServer is essentially just a bunch of tools built on top of a custom Red Hat Enterprise Linux install. Because of this, we have all the flexibility of Linux at our fingertips (this flexibility is what has allowed us to DO the rapid provisioning I just mentioned)
Paravirtualization: Paravirtualization has ALWAYS been Xen’s claim-to-fame. But few people ACTUALLY know what it is and how it works…I’ll spare you the nitty-gritty technical details and put it thusly: Paravirtualization is a bit like Pinocchio, he KNOWS he’s not a real boy; a PV’d guest KNOWS it’s a virtual machine. The advantage you gain from this is that since the OS knows it’s running in a virtual machine, it can better handle the usage of resources like CPU and memory. PV’d guests also have the perk that since they know they’re virtualized, they can talk to the hypervisor and vise versa…the advantage there is that you have the ability to change things live on guests (such as memory usage, disk images, bootloader parameters, etc.) from the host machine that you normally couldn’t with a hardware virtualized guest.
Now I know some of you reading this might still think this article is a LITTLE bit too technical for you…some of you might just want to know what the bottom line is. Well, the bottom line is this: We’re moving into the cloud, you’re coming with us (if you choose, of course 
), and XenServer is what’s taking us there.
It’s the dawn of a new era here at SevenL, and the possibilities afforded to us by XenServer are seemingly limitless. I’ll leave you with this, as well…a little fun fact, if you will. XenServer is the platform currently in use by Amazon for their Elastic Computing Cloud (EC2) service. So if they can do THAT with XenServer…just think of what ELSE could possibly be done with it.