Nice overview of the current situation from InformationWeek's Andrew Conry-Murray. Although it spends a while on the MSFT vs VMW angle, I thought this tidbit on BEA's new LiquidVM-based appliance was interesting -- 25-50% less memory and CPU -- and I assume that's compared to running the JVM on top of Linux.
Applications will always need an operating system to run, right? Not
with BEA's WebLogic Server Virtual Edition, or WLS-VE. It replaces the
conventional OS with LiquidVM, a microkernel-based Java virtual
machine. In turn, the Java VM runs directly on a VMware hypervisor,
without the need for Windows or Linux. "We realized the hypervisor had
eaten into a lot of what an application needs from an OS," says Guy
Churchward, VP and product manager of WebLogic products at BEA.
Java-based applications are ideal candidates for running without a
general-purpose operating system, because they already run inside a
Java virtual machine, which abstracts the OS functionality of Windows,
Linux, and Unix variants. The Java VM provides some OS functions,
including memory and CPU allocation, as well as networking (see chart,
below). BEA added other capabilities, such as input/output management,
that normally are handled by an operating system to the LiquidVM.
Meanwhile, the hypervisor is handling other functions, such as loading
device drivers, which are also usually managed by the operating system.
The result, says Churchward, is that the OS ended up completely
replicating the functionality of the Java VM and the hypervisor.
By jettisoning the OS entirely, Churchward says, WLS-VE consumes 25% to
50% fewer resources, such as memory and CPU cycles, while boosting
overall system performance. Other benefits include reduced management,
because IT doesn't have to maintain a separate operating system.