Updates to enterprise Linux server releases don't typically include rebased Linux kernels. Yet that is indeed what SUSE Linux is doing with SUSE Linux Enterprise Linux Server (SLES) 11 SP2. The new SLES service pack is the first major update to SUSE's flagship platform since the business unit was re-formed as an operating division of Attachmate in 2011.
SLES 11 SP2 includes the Linux 3.0 kernel and provides enterprise support for the Btrfs filesystem. Neither of those items were initially available in the first SLES 11 release back in 2009. SLES 11 SP1 debuted in May of 2010
"We changed our development model in terms of bringing the SLES 11 SP2 platform to market," Kerry Kim, director of solutions marketing at SUSE Linux, told InternetNews.com. "We adopted something that is a bit more forward looking versus the historical approach that had been used."
The traditional approach to Linux enterprise releases is to keep the kernel the same in an effort to maintain compatibility. In that approach, new features are back-ported to the update. SUSE is now taking a different approach and is instead forward-porting compatibility for new features.
Dr. Gerald Pfiefer, senior director of product management at SUSE Linux, noted in the SP1 release that SUSE also rebased the kernel, though in that case it was an exception. With the SP2 update he said there is now a desire and a willingness to move forward instead of constantly backporting technology.
As to the how it's actually possible to include new technologies without breaking backward compatibility, Pfiefer explained that some of the upstream projects have matured. Part of that maturation is a commitment from the projects themselves to have a degree of backward compatibility. SUSE itself has also matured its processes for package inclusion. Pfiefer noted that there are now automated test suites in place to ensure stability of programmatic and binary interfaces.
In cases where that stability isn't in place, SUSE now also has a process.
"As part of an upgrade we can forward port the original interfaces to make sure that whatever was originally there will be present," Pfiefer said.
One of the major new features in SP2 is support for the Btrfs filesystem. Btrfs is a next generation Linux filesystem effort that was originally launched by Oracle. Btrfs provides new snapshotting and rollback capabilities to Linux, that SUSE is expanding upon with the Snapper tool.
Snapper first debuted in the OpenSUSE 12.1 release in November 2011.
"Snapper was a contribution from the enterprise side to OpenSUSE first and now the enterprise side is picking it up too," Pfeifer said.