Hypervisor

Jailhouse

Valentine Sinitsyn — Mon, 08 Jun 2015 17:58:05 +0000

Because you're a reader of Linux Journal, you probably already know that Linux has a rich virtualization ecosystem. KVM is the de facto standard, and VirtualBox is widely used for desktop virtualization. Veterans should remember Xen (it's still in a good shape, by the way), and there is also VMware (which isn't free but runs on Linux as well). Plus, there are many lesser-known hypervisors like the educational lguest or hobbyist Xvisor. In such a crowded landscape, is there a place for a newcomer?

There likely is not much sense in creating yet another Linux-based "versatile" hypervisor (other than doing it just for fun, you know). But, there are some specific use cases that general-purpose solutions just don't address quite well. One such area is real-time virtualization, which is frequently used in industrial automation, medicine, telecommunications and high-performance computing. In these applications, dedicating a whole CPU or its core to the software that runs bare metal (with no underlying OS) is a way to meet strict deadline requirements. Although it is possible to pin a KVM instance to the processor core and pass through PCI devices to guests, tests show the worst-case latency may be above some realistic requirements (see Resources).

As usual with free software, the situation is getting better with time, but there is one other thing—security. Sensitive software systems go through rigorous certifications (like Common Criteria) or even formal verification procedures. If you want them to run virtualized (say, for consolidation purposes), the hypervisor must isolate them from non-certifiable workloads. This implies that the hypervisor itself must be small enough; otherwise, it may end up being larger (and more "suspicious") than the software it segregates, thus devastating the whole idea of isolation.

So, it looks like there is some room for a lightweight (for the real-time camp), small and simple (for security folks) open-source Linux-friendly hypervisor for real-time and certifiable workloads. That's where Jailhouse comes into play.

New Guy on the Block

Jailhouse was born at Siemens and has been developed as a free software project (GPLv2) since November 2013. Last August, Jailhouse 0.1 was released to the general public. Jailhouse is rather young and more of a research project than a ready-to-use tool at this point, but now is a good time to become acquainted it and be prepared to meet it in production.

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ConVirt: the New Tool in Your Virtual Toolbox

Jeramiah Bowling — Tue, 23 Apr 2013 18:29:47 +0000

by Jeramiah Bowling

Virtualization is now a staple of the modern enterprise. As more and more shops switch to the virtual paradigm, managing those new virtual resources is a critical part of any deployment. For admins using Microsoft- or VMware-based hypervisors, powerful management tools are available to keep their virtual houses in order. Unfortunately, those products and their accompanying tools come with a hefty price tag. The good news is that inexpensive open-source virtualization is on the rise, driven in large part due to its low performance overhead. However, one of the primary obstacles to large-scale open-source virtualization adoption has been the lack of robust management tools. virt-manager is the most well known and used, and although it's a great tool, it does not hold a candle to the enterprise tools put out by the big vendors. That's where ConVirt comes in.

ConVirt is an open-source tool capable of managing multiple types of hypervisors including Xen, KVM and now VMware from a single pane of glass. When evaluating ConVirt for your needs, it is best to think of it as a front end to the native tools of the hypervisors that provides extended features not available in a standalone hypervisor. Although there is some overlap with virt-manager, ConVirt adds an additional level of enterprise manageability. ConVirt is currently offered in three tiers: Open Source, Enterprise and Enterprise Cloud. This article focuses on the open-source version. The open-source version does not include the ability to manage VMware items, so the testing environment for this article contains only Xen and KVM servers. Even though I don't cover it here, the ability to manage VMware hosts along with KVM and Xen hosts from the same pane of glass should peak the interests of many admins.

Let's get started by installing the ConVirt Management Server or CMS. ConVirt can be installed on most flavors of Linux or as a pre-configured virtual appliance that can be imported into a KVM or Xen server. I chose to deploy my CMS on a physical server running CentOS 6.2 to allow plenty of storage space (the virtual appliance is roughly 2–3GB in size), although the appliance probably will get you up and running faster. Make sure that whichever installation method you select, that you open all the necessary ports on your CMS and on your managed servers/hosts that you want to manage through the console (TCP 8081, 8006, VNC ports and SSH).

The term "managed server" refers to those hosts running a hypervisor that is managed by ConVirt and can be used interchangeably with the term "host". Follow the installation procedures available on the Convirture Wiki site to perform the installation of the CMS. Most of the install is handled by a script that pulls down the dependencies and installs MySQL. I won't go into finer detail on the server install, as it is well documented on the site and I would just be repeating the information here.

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Xen Enters Mainline Kernel

Michael Reed — Mon, 20 Jun 2011 13:00:00 +0000

by Michael Reed

Future versions of the Linux Kernel (such as 3.0) will include support for the Xen hypervisor. This means that Linux distributions will typically offer out of the box support for both hosting Xen and running as a guest operating system under Xen.

Xen requires operating system support from both the host and the guest. In other words, you need an operating system that has been modified in order to run Xen or to run under Xen. [Correction: Xen can run unmodified operating systems on a processor that supports x86 virtualisation, which to be fair, should include most modern desktop processors.] In the past, installing Xen (in most distributions) has been a more complicated procedure than for other virtualizers such as VirtualBox.

As it stands, the Linux Kernel offers support for KVM, a virtualization technology that can speed up the QEMU machine emulator. It is the hope of the Xen community that out of the box support for Xen will increase adoption. However, the degree to which built-in kernel support will raise the profile of Xen is debatable. The target of Xen has always been server admins who placed a higher premium on top-flight security and server specific features than they did on ease of use. Anyone who needs the features that distinguish Xen from other solutions would probably not have been dissuaded from using it by the difficult installation. Casual users, who need a simple installation via the package manager on distributions such as Ubuntu, would probably be better served by VirtualBox, QEMU or VMWare.

Who knows, perhaps someone will cook up a virtualization solution aimed at casual desktop users, but that uses Xen as its underlying technology? There might even be some scope for adding other features, such as application sandboxing, by making use of Xen.

The announcement on the Oracle website.

The image that I used in this article, a picture of a zen garden, was taken from the Flicker account of CyboRoZ. I was able to use it here because it of the Creative Commons license that he released the work under.

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