VMs

VirtualBox 4.1 Introduces Cloning Amongst Other Features

Michael Reed — Thu, 28 Jul 2011 14:52:57 +0000

We first covered the release of VirtualBox 4.0 back in January. Amongst other improvements and new features, 4.1 adds VM cloning and a nascent PCI passthrough feature.

The new cloning feature allows the user to easily make a copy of an existing VM including the hard disk image and all associated settings. It’s going to be particularly handy for people like me who create a lot of blank VMs with similar specs. This means that I can create a generic Linux 2.6 supporting VM with 1GM of RAM and a virtual HD of 8GB and then simply clone it when I need a new one. The speed of the cloning procedure varies according to the size of the HD file. For example, cloning a fresh VM with an unused dynamically scaling hard disk image takes almost no time, whereas cloning my Windows XP VM with a 4GB partition took a few minutes.

Virtual disk management has received a couple of useful enhancements. It is now possible to directly create and work with VMDK (VMware) and VHD (Microsoft Virtual PC) formats from the GUI. There is also a GUI interface for copying hard disk images. As with the cloning features, the new hard disk management features were already more-or-less possible from the command line and with a bit of extra trouble, but having them built into the GUI will be more convenient for those of us who prefer to work that way.

PCI Passthrough, a new Linux only feature looks intriguing, but according to the docs, it seems to be at early stage with limited hardware support. The feature allows guest operating systems to directly access PCI and PCI Express hardware, even in cases in which the hardware is not supported by the host. This could offer benefits in two main areas: Firstly, it offers the potential to greatly improve the performance of hardware such as network adaptors when accessed from within a VM. Secondly, it would allow Linux to use hardware (albeit via a VM) that either has no, or only limited, Linux driver support. For the moment, only specific combinations of motherboard chipset and add on card are supported. Something tells me that this is a feature worth watching out for in the future. See the appropriate section of the manual for more info.

Note that version 4.1 increases the memory limit to 1TB for 64 bit guests. So, it looks like developers are already thinking about support for KDE5. A new GUI for setting the CPU cap makes it possible to limit the amount of processor time that a VM can gobble.

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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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Consolidate: Put Your Servers into a VirtualBox VM

Michael Reed — Thu, 30 Sep 2010 13:00:00 +0000

by Michael Reed

Rather than installing a server, such as a web server, directly onto your main computer, why not install it in a VM? This sort of setup has a few advantages of security and convenience. These days, spreading resources out into the cloud is the in-thing, but consolidation is often underexploited. Hosting a server in a virtualizer such as VirtualBox is often a good approach for casual or occasional server needs on a home network.

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