Oracle juices homegrown Xen to match own-brand Linux
One Ellisonized kernel to bind them all
System maker Oracle has upgraded its version of the Xen server virtualization hypervisor with its own variant of the Linux kernel to bring it in synch with its Enterprise Linux server operating system distro.
The new Oracle VM Server also includes some nips and tucks specifically for admins babysitting hypervisors.
A bare-metal hypervisor is just a very specific kind of operating system that has been chopped down to its essence and that is designed expressly to run virtual machines that in turn support other operating systems side-by-side on a single piece of iron. So it is not surprising that Oracle wanted to get the Unbreakable Enterprise Kernel R2 software  inside its Enterprise Linux distro, which was announced back in March, to be the foundation of its Oracle VM Server Xen hypervisor.
Specifically, Unbreakable Enterprise Kernel R2, which is based on the Linux 3.0.16 kernel, is now the dom0 kernel for the Oracle VM Server release 3.1. (The kernel will however report that it is at the 2.6.39 level, but ignore that.) By moving to UEK2, any driver that runs on Enterprise Linux will run on Oracle VM Server; whether or not these drivers are loaded and exposed is another matter entirely, since some things you want to run on a server you don't want running in your hypervisor.
"This is possible because of all the work we have done together with Citrix/XenSource people over the last few years to get the necessary support for Xen and Linux merged into Linux," explains Wim Coekaerts, senior vice president of Linux and virtualization engineering at Oracle, in his blog  announcing the new hypervisor.
"As I have mentioned in a previous blog entry, Linux mainline contains everything needed to have Linux be a complete dom0 management kernel for Xen without any additional patches. Unlike some of the FUD out there about Xen not being part of Linux, we have always made clear that Xen is a hypervisor," he continued. "And Linux runs on top as the management/control domain kernel giving a great level of separation/isolation. In enterprise environments this is a big deal and helps us create solid, stable, secure solutions."
On top of its UEK2 kernel, Oracle has plunked the open source Xen 4.1.2 hypervisor, which is the latest release  from the open source Xen community that came out in October 2011  and that includes enhancements to the paravirtualized driver stack for Xen. Oracle says that its paravirtual drivers (which are at the 3.0.1 release) have been put through the Microsoft paces and have been validated to pass Microsoft's tech support muster through its Server Virtualization Vendor Program (SVVP).
You can read the Oracle VM Server 3.1 release notes here  and an overview document there  (PDF). By moving to the new kernel, the underlying Oracle VM hypervisor can now span up to 4TB of main memory which it can virtualize and carve up for virtual machines to romp within. The 3.1 release also has the ability to hot-add virtual CPUs to running VMs, which is particularly useful for workloads that need to scale up quickly.
The 3.1 release also has some new features when it comes to VM templates. You can now move a VM and its templates to a different repository on your network but keep all of its parameters – including the all-important MAC address – constant as it bops around. Or, you can clone a VM or template and have it substitute a different MAC address for the virtual machine so the original VM and its clone can run side-by-side on the network without interrupting each other.
There's also a one-click button in the Oracle VM Server Manager console that allows for multiple virtual machines to be spawned from a single template with a single mouse click, and one admin that is in control of a VM can now pass off control of that VM to another VM without pausing it. Oracle has also woven in updated templates for its systems and application software, including those for Oracle E-Business Suite 12.1.3 applications; Oracle PeopleSoft FSCM 9.1; Oracle Enterprise Manager Cloud Control 12c; Oracle Linux 5.8; Oracle Linux 6.1; and Oracle Solaris 11 11/11. There are now more than 100 templates for Oracle code that are ready to be sucked into an Oracle VM Server environment and booted up.
Oracle has also polished up the Oracle VM console GUI, adding wizards for newbies and the ability to drop and drag VMs and apps as you build virtual machines. The virtual machine also does keyboard mapping for different languages for each VM console and for pools of virtual machines. The console also knows how to do bulk discovery of virtual machines on the network through hostnames and IP addresses.
Storage features got some tweaks with Oracle VM Server 3.1 as well, with VM storage repositories based on Oracle Cluster File Services version 2 (OCFS2) allowing for the storage repository to be moved from one server pool to another one; these OCFS2 repositories can also expose an NFS share to allow for backup and restoring of VMs as well as templates, assemblies, and ISO images. Also, if you resize a LUN associated with a VM, the OCFS2 file system will automagically resize itself to match. Finally, the hypervisor now also supports multipath booting from the SAN, which means you don't have to have local storage on the server for the hypervisor but you can still eliminate a single point of failure if you want to boot the hypervisor from the SAN.
Oracle distributes its VM Server hypervisor for free. Oracle's own Solaris 10 and 11 and Linux 4, 5, and 6 distributions (the latter being RHEL-ish clones) can run on top of the bare-metal hypervisor, as can Red Hat Enterprise Linux 4 and 5. Microsoft's Windows Server 2003 and 2008 as well as Vista and 7 desktop operating systems can run on it as well.
While the underlying kernel can support 4TB of memory, if you look into the release notes it says the hypervisor tops out at 160 cores and 2TB of main memory with a total of 128 virtual machines per hypervisor. Virtual machines can have up to 128 virtual CPUs, 63GB of virtual memory on 32-bit guests and 1TB on 64-bit guests. ®