Commercial Linux distributor Red Hat is hosting its annual summit in Chicago this week, and the star of the event was today's launch of Red Hat Enterprise Linux 5.4, which sports the first commercially supported KVM hypervisor from the company.

In this case, KVM is tucked up inside of RHEL 5.4, right alongside the integrated Xen hypervisor that customers have been able to deploy since RHEL 5.0 was launched in March 2007. When Red Hat caught the virtualization bug several years back, Xen was the horse to back, and Red Hat did, just like Novell, Sun Microsystems, Oracle, and others did. But KVM is, according to Red Hat, a leaner and meaner hypervisor and is integrated into the Linux kernel already, so it has some benefits compared to Xen.

But the main benefit is that Red Hat, after its $107m acquisition of Qumranet - the company that sponsored the KVM hypervisor and some related tools for managing virtualized desktops called VDI Manager - can control the fate of KVM and therefore have an easier job integrating hypervisor and operating system functions and the tools to manage them. The other benefit is that because KVM is part of the kernel, Red Hat can guarantee that any of the more than 3,000 applications certified for RHEL will work atop the KVM hypervisor with no changes. Oh, the final benefit is that Red Hat can make money off all that.

According to Paul Cormier, president of products and technologies at Red Hat, who spoke at a press conference from Chicago with Brian Stevens, Red Hat's chief technology officer, and Navin Thadani, senior director of the virtualization business, the complete stack of KVM-related products went into a beta program back in June, not just the standalone KVM-based hypervisor, which is called Red Hat Enterprise Virtualization. More than 100 customers have been playing with the freestanding RHEV hypervisor and RHEL 5.4 as well as tools for managing servers and PCs that have been virtualized with either.

The complete Red Hat virtualization product stack, which the company laid out back in February when in announced its intentions in the virtualization arena, includes RHEV, which Stevens said is a stripped-down hypervisor that will weigh in at about 100 MB, as well as the integrated KVM hypervisor in RHEL 5.4. The KVM hypervisor comes from the identical code base, the difference is really how customers want to consume and manage it.

Red Hat is also tweaking and extending Qumranet's VDI Manager, which could manage thousands of virtualized PCs, so it can manage servers too, and then splitting it into two products: RHEV Manager for Servers and RHEV Manager for Desktops. These management tools will complement the provisioning and patching that comes through Red Hat Network Satellite, which has just been upgraded to version 5.3 this week, but it is the RHEV tools that will include live migration, high availability, system scheduling and load balancing, power capping, monitoring, and reporting - and other features needed to manage virtual machines.

RHEV and these two management tools will be available sometime in the second half of this year, but apparently something is coming out in the next few weeks. It might seem odd that KVM is being rolled into RHEL 5.4 first with the management tools missing, but Stevens said that some companies are perfectly fine using their own management tools and just want RHEL with KVM, and it being ready, Red Hat was happy to provide it. It stands to reason that RHEV will come out next, perhaps with desktop tools (which were already mostly done thanks to Qumranet) followed by server management tools later in the year.

Stevens was clear that the company and its customers did not want to wait until RHEL 6 came out to get KVM into the field, and it added that the company was working on features to allow the "refactoring" of virtual machines based on other hypervisors so they could be converted and run atop KVM. Red Hat is keen, of course, in allowing the conversion of from Xen to KVM formats. But Stevens also hinted that Red Hat was working on tools to allow conversion from other hypervisors and mentioned VMware's ESX Server by name.

Hyper-V also makes sense, and an interoperability deal that Red Hat inked with Microsoft in February the week before it threw its, er, red hat into the virtualization ring will presumably be used to ensure this happens. The trick is being able to figure out what specialized drivers are being used by customers using one hypervisor and finding the equivalents with another hypervisor and installing them on the fly. The issue is larger than simply supporting the OVF disk format for storing a VM image.

According to the RHEL 5.4 release notes, customers can install Xen and KVM on the same machine at the same time, but they require different kernels and different network settings. Red Hat says you really shouldn't do two hypervisors at once. The KVM hypervisor inside RHEL 5.4 will support RHEL 3, 4, and 5 as well as Windows XP, Windows Server 2003, and Windows Server 2008 as guest operating systems.

Red Hat says customers should not use its Cluster Suite tools to failover KVM images just yet, since this capability is only in tech preview. The ext4 file system is still in preview as well, the company warns, and so is the Maloc memory allocation library for multicore processors.

RHEL 5.4 includes performance tweaks for Intel's quad-core Xeon 5500 processors and Advanced Micro Devices' six-core Opteron 2400 and 8400 processors. The SystemTap system probing tool us now fully supported and has been updated too. Fibre Channel over Ethernet drives have also been enhanced. ®