Well-known Linux kernel developer Ted Ts'o announced this week that he has joined Google, leaving behind his previous role as CTO of the Linux Foundation. Ts'o, an expert on filesystem development, played a central role in creating Ext4, the latest generation of the dominant Linux filesystem.

In a statement on his blog, Ts'o expressed enthusiasm for his new job and pointed to a recent mailing list post by a Google engineer which reveals that the search giant is in the process of upgrading its storage infrastructure from Ext2 to Ext4. Ts'o says that he will continue working on Ext4 and other parts of the Linux kernel while he is at Google.

His departure from the Linux Foundation is not sudden or unexpected—the organization has an informal policy of rotating people through the CTO position at regular intervals. When Ts'o took the job in 2008, he came from IBM and it was understood that he would serve a two-year term with the foundation. With his term completed, he has decided to join Google instead of going back to Big Blue.

Ext4 faced some criticism during its development following the discovery of possible data loss issues relating to the filesystem's implementation of delayed allocation. Ts'o created patches that have addressed those issues, minimizing the potential risk. Google's decision to deploy Ext4 is a strong endorsement of the filesystem's reliability and affirms its suitability for enterprise adoption.

In a mailing list post, Google engineer Michael Rubin provided more insight into the decision-making process that led the company to adopt Ext4. The filesystem offered significant performance advantages over Ext2 and nearly rivaled the high-performance XFS filesystem during the company's tests. Ext4 was ultimately chosen over XFS because it would allow Google to do a live in-place upgrade of its existing Ext2 filesystems.

"The driving performance reason to upgrade is that while ext2 had been 'good enough' for a very long time the metadata arrangement on a stale file system was leading to what we call 'read inflation'. This is where we end up doing many seeks to read one block of data. In general latency from poor block allocation was causing performance hiccups," he wrote. "For our workloads we saw ext4 and xfs as 'close enough' in performance in the areas we cared about. The fact that we had a much smoother upgrade path with ext4 clinched the deal."

The Linux Foundation has not yet announced who will be the organization's next CTO. It would be fitting for the foundation to use its newly-announced Linux Jobs board to find a worthy candidate, but it's more likely that the organization will pick someone from their growing roster of member companies.