Xen

When you have been in this industry for a couple of years, you might think that the Virtualization industry has stopped innovating, that there are no new awesome features coming out anymore.

Obviously they aren’t coming at the same pace as 5-10 years ago anymore, we aren’t surprised anymore when people add Virtualization support for yet another CPU or publish yet another new and fresh management framework, with a cloud sauce .. But hidden far in the back corner innovation still happens, be it with much smaller and less intrusive steps than before.

So lets have a look at these small changes

First of all a project I’ve been following for a while now .. XenFS , XenFS builds on the idea that you often want to share filesystems between virtual machines on the same physical machine and that you don’t want to use NFS, Cifs or even the regular network stack to achieve this goal.

According to Mark Williamson who’s working on the project :

The major differences from a traditional network filesystem are in the implementation. XenFS is implemented as a XenLinux “split driver”, with kernel modules implementing the client and server portions. Instead of exchanging protocol messages over a network socket, XenFS exchanges requests and responses using shared memory, similar to the “device channels” used by the block and network split drivers. Beyond that, instead of copying data from the server to the client (and back) XenFS also shares the memory containing the actual file data.

XenFS has been around for a while, but KXen is actually brand new. Argumenting over the advantages and disadvantages of a TypeI vs TypeII hypervisor is now over as Xen “supports” both.

Stephen Spector announced the availability of the first public release of Hosted Xen (KXen)

According to Stephen

Xen is the leading open source Type-1 VMM, providing a fast, robust and secure virtualization platform. KXen leverages the Xen technology, extending the range of environments in which the same core engine can be used to existing desktops, laptops and allowing scenarios like run from usb stick.
Work is underway to support MacOSX as the host, as well as 64-bit versions of Windows. The windows 32-bit host code is designed such that it is easy to port to other host operating systems.

The Remus project which we covered earlier , has also released it’s initial Request for Comment code. Remus allows systems to transparently move to another physical machine in the event of a failure on the primary machine , with only seconds of downtime, while preserving the original host state such as active network connections , memory and disk state.
Being an RFC release means that it is meant to start a discussion on how it might be merged with Xen and Kemari. According to the announcement it is not by any means in shape for application to the Xen tree
But it is a giant step forward towards a better high availability solution using Virtualization.