Red Hat Enterprise Linux Says Goodbye to Xen

Red Hat’s latest beta of RedHat Enterprise Linux version 6 has popped up, and there’s a plethora of new features. But there’s also one feature missing, and it’s not a mistake. Xen hypervisor is conspicuously absent, and there’s good reason why. Read on…

ComptuerWorld’s Joab Jackson had a solid rundown on the latest beta of the OS, noting that it should help data centers handle virtualization and cloud computing much better than in the past. But then why the drop with Xen? it should come at no surprise that RedHat has been focused on the alternative KVM (kernel-based Virtual Machine) and have decided to put all their energy into supporting it, instead.

But what’s so special about KVM that Xen needs to get dropped entirely? Tim Burke, Red Hat vice president of platform engineering noted that especially for cloud deployments, RHEL 6 dynamically allocates kernel data structures. And because of this “…it will allow cloud service providers to give better service-level agreements,” Once a VM gets loaded into the OS, an admin can much more easily tweak the settings and resources the VM gets allotted.

It’s also important to note that in 2008, RedHat acquired virtualization guru Qumranet, which developed early KVM software. What’s more, Burke felt that resources were being utilized to develop duplicated capabilities and felt it wasn’t an efficient use of manpower.

And as for the other new features? The CFS, or Completely Fair Scheduler is designed to balance workloads among tasks, equalizing and distributing system resources where they need to be. Priority level is a focus.

There’s also power saving features, too. A unique features dubbed “tickless kernel enhancement” has been deployed to fix an issue where the kernel would talk to the CPU every 1,000 times per second for time measurements. This prevent the CPU from going into power-saving sleep mode. With ‘tickless’ quiet time means sleep time for the hardware, and by the transitive property, power savings too.

EXT4 has also become the default file system, and allows for 16 terabyte file systems, plus the option for SGI’s XFS file system, which allows for 128 terabytes.

ComputerWorld also reports that….

“Simon Crosby, a co-founder of XenSource and currently Citrix’s chief technology officer for platform software, said that he wasn’t surprised by Red Hat’s decision to drop Xen. (In 2007 Citrix acquired XenSource and now offers commercially supported versions of the open-source Xen hypervisor.) It makes sense to only support one code base, and Red Hat has not contributed to the Xen code base for several years.”

But there was a bit of a word joust:

“Crosby also noted that, with Xen, Red Hat did not have much luck in marketing virtualization. “Red Hat has been lousy at enterprise virtualization. They failed at bringing Xen to the market. Now they’re five years behind the rest of the community,” Crosby said.”

Criticisms aside, the bottom line is that this reworking of RHEL will lead to some Xen-based VMs needing to get re-installed or migrated over to KVM when RHEL 6 goes mainstream. Burke did indicate there would be a migration conversion tool, but lost time is lost time. Version 6 is scheduled to debut on a few months, but Burke didn’t comment on a official date.

RedHat friends and partners — what’s your thoughts on this? No big deal, or an inevitable headache when the update arrives?

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