"Despite the fact that Ext4 adds a number of compelling features to the filesystem, T'so doesn't see it as a major step forward. He dismisses it as a rehash of outdated "1970s technology" and describes it as a conservative short-term solution. He believes that the way forward is Oracle's open source Btrfs filesystem, which is designed to deliver significant improvements in scalability, reliability, and ease of management."
-http://arstechnica.com/open-source/news/2009/04/linux-collab...
Theodore Tso is the main developer of ext4 and numerous times he has said that it is simply another step forward, nothing new or remarkable, and that he believes that btrfs will be the implementation that really pushes the envelope for filesystems. Why is google moving to ext4? Why not wait/get involved with the development of btrfs? Does google know something about btrfs that nobody else does? If they want stability, why not just stay with ext2? I feel a lot of important facts are being left out of this advertised switch.