Over the years, the server virtualization strategy at Sun Microsystems has been spotty, but recently it has been evolving to include a variety of new techniques. Dynamic domains, Solaris containers, logical domains, and on x64 iron, support for Xen and ESX Server hypervisors are all part of the fare now.
Sun bought its way into the desktop virtualization arena this past February, and it is determined to be a player here, too, even if its own desktop - well, workstation - business has pretty much dwindled to nothing.
The 8 million downloads of VirtualBox - half of them since Sun took over German software company Innotek - make Sun a player of sorts in desktop virtualization, which is even greener (in terms of youth, not energy efficiency) than server virtualization. Innotek launched a virtual machine hypervisor for Windows, Linux, and Mac OS X desktops and laptops just a little under two years ago, and oddly enough got its start creating virtualization products for IBM's and Microsoft's jointly developed OS/2 operating system.
The product was rebranded xVM VirtualBox in May when the 1.6 release came out. At that time, Sun gave VirtualBox native Solaris support, which means that Solaris 10 (the commercial version of Sun's Unix) or OpenSolaris (the development version) can act as either a host operating system for the VirtualBox hypervisor or run as guest environments atop the hypervisor, which itself runs on the host OS. (VirtualBox is not what is called a bare metal hypervisor, like VMware's ESX Server, that allows multiple operating systems to run side-by-side while still thinking they own all of the hardware in the box, which they do not.)
VMware Server, the freebie hypervisor, and VMware Workstation, the desktop variant from that company, run atop a host operating system, just like VirtualBox does. The practical difference between the bare metal and host-guest hypervisors is that the host operating system is a single point of failure for all of the partitions on the machine, while the less-complex hypervisor is (presumably) using less resources and is more rugged, stable, and secure. That's the theory, anyway.
To my way of thinking, a hypervisor has all the same issues as a host operating system and only benefits from its simplicity and obscurity. Like ESX Server, VirtualBox doesn't require the hardware-assisted virtualization electronics in the latest x64 chips (Intel VT on Core and Xeons and AMD-V on Opterons) to work, but it can make use of these features to support ancient operating systems, such as OS/2.
With VirtualBox 2.1, Sun is tapping the Intel VT-x (the variant of VT for x64 chips) to boost the performance of the Mac OS X operating system when it's being used as a host for OS X and other operating systems running the VirtualBox hypervisor. The 2.1 release also providers support for the desktop variants of the "Nehalem" processors, known as Core i7, and their related QuickPath Interconnect.
Sun is also adding experimental support for the OpenGL 3D graphics acceleration for Windows guests running VirtualBox, and this 3D support gets passed through from host operating systems (Windows, Mac OS, Linux, or Solaris) to the Windows guest operating system. Only 32-bit Windows Vista and Windows XP guests can access this OpenGL support, and the Direct3D alternative from Microsoft is slated for a future release.
The OpenGL support will make Google Earth work properly, which is a very important feature (that was sarcasm), and the future Direct3D support will make Microsoft virtual Earth work, too.
The tweaked VirtualBox will also allow a 32-bit host operating system running on 64-bit hardware to support a 64-bit guest operating system; you'll notice this support is experimental, if you read the release notes carefully. Sun also says that it has "improved" support for VMware's VMDK and Microsoft's VHD virtual machine disk formats along with the program's own VDI native VM disk file format.
VirtualBox can also import VMDK and VHD virtual machines (provided the guest OS levels are supported) and do snapshots of the VM files in these three formats. Sun says VirtualBox 2.1 also has tweaks to improve virtual network performance, and sports an iSCSI initiator driver that allows VirtualBox to access VM images stored on iSCSI disk arrays.
You can get VirtualBox 2.1 here, and if you want, you can grab the open source code and play around with it. Sun also offers 24/7 premium support contracts for VirtualBox, which run $30 per user per year.
Interestingly, Sun says that VirtualBox downloads have more than doubled compared with last quarter and that user registration is up 24 per cent. (There are 8 million cumulative downloads of all VirtualBox releases to date, but only 2.5 million registered users. People don't like to fill out forms.)
Sun has given no indication as to how much - or how little - money VirtualBox generates. And the company has yet to explain where VirtualBox will fit into its server virtualization strategy, if at all, in the long term. ®