The Year in Operating Systems: No battle of big ideas
Small change for 2009
March of the penguins
Speaking of Linux, the operating system must be maturing, because its development cycle is starting to have the predictable cadence of a Unix platform from the 1990s. While there are dozens of different versions of Linux the three that mattered most for servers were still largely under the control of Red Hat, Novell, and Canonical - namely Red Hat Enterprise Linux, SUSE Linux Enterprise Server, and Ubuntu.
We can argue whether or not Linux mattered all that much on desktops this year. I think netbooks proved there is a place for Linux where users can see it, and there are certainly plenty of phones and other hand-held devices where you don't really see Linux that were eagerly snapped up.
In the case of Red Hat and Novell, there are development versions of the code, managed by the respective Fedora and openSUSE projects. This code is grabbed, hardened, and tested for application compatibility and then distributed as RHEL or SLES. So what did they deliver?
RHEL 5.2 shipped in May, and the beta of RHEL 5.3 was released at the end of October, possibly for shipment sometime around January 2009. RHEL 5.2, based on the Linux 2.6.18 kernel, doubled the core count supported in a server to 64 cores and pushed main memory support up to 512GB in a single image.
The Xen hypervisor inside RHEL 5.2 was updated to be able to see the NUMA-style motherboard clustering used in big iron servers, which allows a virtual machine to span more than a single processor socket. Red Hat had added support for Advanced Micro Device's quad-core Opterons as well as Intel's still future octocore processors codenamed Nehale - (due in maybe late March 2009) way back in RHEL 4.6.
Interestingly, Red Hat's implementation of the Xen hypervisor embedded inside RHEL ran on Intel's Itanium processors as well as x64 iron. The company is in the midst of shifting from Xen to KVM for virtualization. The latest Fedora 10 delivered KVM as the default hypervisor, with Xen as an option. It won't be until RHEL 6 is launched later in 2009, though, that KVM is the default on the commercial versions of Red Hat's Linux.
RHEL 5.3 will support up to 126 processor cores in the hypervisor (not 128, unless the release notes have a typo) and up to 1TB of main memory. The update will also sport "extended support" for Intel's six-core Dunnington family of Xeons and the future Nehalems. It will also sport a technology preview of the ext4 file system, iSCSI boot, and 32-bit paravirtualized operating system guests on 64-bit x64 hosts.
Novell delivered SP2 for its SLES 10 server and its SLED 10 desktop variants in May, and as in the past, the company tried to get the jump on Red Hat in terms of the level of the Xen hypervisor it embedded in its Linux variant.
Thanks to its partnership with Microsoft, Novell was also bragging that SLES 10 SP2 was the only Xen-based hypervisor with support for Windows Server 2003 and Windows Server 2008 as a guest. And now that Hyper-V is available, Novell also claimed it was the only implementation of Xen that offered "bi-directional compatibility" between Linux and Windows for guest operating systems. Presumably that meant live migration back and forth between those two platforms of those guests.
Novell has been mum about endorsing KVM as a hypervisor, but since KVM has been mainstreamed into the Linux kernel, such an endorsement is not a big deal technically. Microsoft had a partnership with XenSource (now a part of Citrix Systems) to create Hyper-V and ensure its compatibility with Xen, and it is not clear what might be involved to get SLES and Hyper-V to be compatible with KVM.
Clearly, if KVM takes off, all of the work that Novell and Microsoft have done to be Xen friendly will have gone largely to waste.