During the Fosdem 2008 conference, we had a chance to sit down (on a bench) with Xen Guru Ian Pratt. Below is the second part (watch the first part here) of our exclusive interview, where Ian shines his light on the Xen GPL license, OracleVM, xVM (Sun), the future of virtualization and XenServer.
We cut the interview into 4 digestable pieces, which we publish one at a time. As said, this is the second part (you can also find a written transcript below for your convenience):
This video is also available on Vimeo and Streamocracy.
(0:02) Could Virtualization also help the infrastructure to become more self-healing or self-provisioning?
“Sure. It is already the case that you can have a pool of physical hardware. Something that Xen calls a resource pool and than a pool of VMs running on top. You can configure things as the referrer to give “down notices”, so you can fail over those virtual machines. There are plenty of people who do that today on Xen.”
(0:31) When I look at the Xen GPL-license. I find it interesting that Xen is being renamed as xVM by Sun, OracleVM by Oracle. When Oracle first announced OracleVM it quickly had to admit it was actually a tweaked Xen version. I heard they initially did not publish the tweaked code.
“Oh no, they have. The fact is that there are lots of different vendors, shipping Xen products as they pick up the Xen hypervisor core engine and incorporate it into their own products. The Linux vendors: like Novell and Redhat, there is Sun, there is obviously XenSource / Citrix and Virtual Iron. Lots of different companies are doing that. Actually the GPL license means that any changes they make will go back into the main project. In reality, pretty much all those company just pick it up as is. They take the latest stable release, which is maintained, they might add the odd little patch to it, but it really is all very clear, there is a lot of uniformity in the Xen versions out there.”
(1:40) As many of these projects like Sun’s xVM and Oracle’s VM are using the Xen project. At what level are they tweaking their own software to be more integrated with Xen or to be more stable or faster?
“Most of those companies are very close to mainline Xen. They post a couple of patches. In some cases they maybe not. What they will be doing, is taking Xen and it’s really on top of Xen , in the rest of their Virtualization stack (that runs in user space) that’s where they’ll be probably doing their own things. They might have their own management tool. They will have their own way of wanting to present virtualization to the user. So if you think about what the operating system vendors are typically doing, is they want to expose virtualization using the same tools and user interfaces as they use for exposing other facilities inside that operating system. Which is quite different from what a company like XenSource was trying to do, which tried and effectively build a virtual machine hosting appliance. You just put the CD in the server, install it and just manage it from a windows GUI or web interface. Every company is bringing Xen to market in a different way for a different kind of user. And that is where the differentiation happens. The core engine is the same throughout.”
(03:31) You think that is what the future will bring us? You buy a piece of hardware and just initiate it, to install an operating system.
“I think it will go way further than that. We have always envisioned getting Xen embedded in the firmware as we think that the hypervisor is a core part of the platform. We think it should come with servers when they role of the production line and they should all have Xen installed on them. And the really cool thing is that this is happening. Dell is already announcing that in their new servers shipping later this year, Xen will be a factory installed option in flash memory. Other hardware vendors are to follow soon. People will have ubiquitous virtualization, every server will have Xen installed on it. You will be able to install multiple operating systems and virtual appliances, etc. on top of the hardware.”
(04:33) So now the x86-type of servers are becoming very similar to what mainframes are used to for decades?
“Exactly, it will be a similar model. The difference will be that you can start using these x86-servers, connecting them into resource pools and than running pools of VMs on top of these pools of servers. That is when things start becoming really interesting.”
(04:58 ) You think people will need to rethink their whole infrastructure even more drastically than they do today?
“Yes, today virtualization is typically used for sort of server consolidation. Often used for taking legacy applications or old versions of operating systems and consolidating them onto a single machine…
I think that the way that things are going to be tomorrow and start happening today (and for which Xen is brilliantly prepared) is actually for running production workloads, where all of your machines and partners are running hypervisors and that enables you to run any virtual machine image on any physical machine to take advantage of being able to move workloads around by using live relocation. Also balancing of VMs to servers and even features like fault tolerance and the stuff we talked about, which you want for production workloads.”
(05:59) If you ask people to name a virtualization vendor, VMware will probably come up first. They definitely have a track record to have built this market. But if you look at really big IT-datacenter applications like Amazon, Google or MySpace, they actually deployed Xen as their core engine. It appears all of the Fortune top 100 companies in the United States are VMware clients. So why do banks go for VMware and these major datacenters for Xen?
“I think you will see plenty of banks switching to Xen and plenty of them already have, as it is obviously a lot cheaper to deploy Xen. The reason that companies such as Amazon go with Xen, is that when you do these large virtualization deployments, you want to be using something to secure great performance and some of the high-end second-generation virtualization features. Xen certainly has all that and also has the advantage that it is open source. So there is not going to be vendor lock-in, with a number of different Xen-vendors to procure from and the price is right. For a sophisticated company like Amazon, they will just download the open source version and they will have 20 engineers deploying it across machines. There are plenty of other companies that will rather tank one of the pre-packaged versions from one of the Xen-vendors. I think that many of the large virtualization deployments -such as Amazon- are on Xen because it works better.”