The VirtualBox hypervisor now under the control of Oracle - if any open source software project can be said to be under control of any corporation - has been updated with a 3.1.6 release.
The 3.1.6 maintenance release follows a true "major" release that came out of the project last November, when VirtualBox 3.1 was given the ability to migrate live partitions of running software from one physical machine to another - something all the cool hypervisors these days have to do. That live migration can occur between any two machines that share a TCP/IP link and have access to the same iSCSI storage using either the NFS or Samba/CIFS file system, and it works with Solaris, Linux, Windows, or Mac OS being the host environment for the VirtualBox hypervisor.
With the 3.1.6 release, the hypervisor fixes the stability of the virtual symmetric multiprocessing code used when guest partitions span more than one physical processor and also fixes some issues with the VT-x hardware-assisted virtualization inside of Intel's Core and Xeon processors. Some problems with the asynchronous timer mode on machines running the Linux 2.6.31 or later kernels on their hosts and some suspend/resume operations on Linux 2.6.30 or later hosts were fixed. Perhaps most importantly for the developer community that likes VirtualBox, the hypervisor has been tweaked to support the impending Ubuntu 10.04 release, which Canonical expects to announce on April 29.
VirtualBox is arguably one of the most popular products that Sun Microsystems ever
had acquired, with more than 20 million versions of the hypervisor distributed between February 2008, when Sun bought its creator, Innotek, and the launch of VirtualBox 3.1. At the time, Sun said that VirtualBox was being downloaded at a rate of 40,000 copies per day. So the installed base should be well over 25 million by now. (In the time it took you to read this paragraph, a few more copies were distributed).
While Oracle gave VirtualBox a little love when discussing its Solaris, Linux, and virtualization plans in January in the wake of the closed acquisition of Sun, the company has not released a roadmap for what it plans to do with the software next. Oracle thinks that creating and testing stacks of software inside VirtualBox is a fine idea for developers, but it wants for them to use Oracle VM or Solaris containers to encapsulate applications or on Sparc T-based iron that supports them, use logical domains (LDoms).
Despite the fact that VirtualBox is a type 2 (meaning hosted, not bare metal) hypervisor unlike XenServer, Hyper-V, and ESX Server (or LDoms and Oracle VM for that matter), the product certainly can be used in production environments and is well regarded. It can support guests with up to 32 virtual CPUs per guest VM, can run 32-bit or 64-but guests with or without assistance from the processors (VT and AMD-V features), and also uses the Open Virtualization Format (OVF) to describe VMs. (OVF is trying to become a standard, but needs to have a file system as well as VM descriptions and metadata to become a true standard for packaging up VMs).
What Oracle has not done since taking charge of Sun, and therefore VirtualBox, is tell its community what its plans are to extend this tool. It seems unlikely that Oracle would transform VirtualBox into a bare-metal hypervisor, since it has already back Xen - twice, if you count the acquisition of Virtual Iron last year, and three times, if you consider Sun's xVM Server attempted clone of Xen for x64 servers. You can't beat the price of VirtualBox: free, with an open source variant, plus $30 per year per machine for 24x7 technical support on a PC and $500 per year for every four sockets on a physical server.
You can download VirtualBox 3.1.6 here. ®