Google upgrading to Ext4, hires former Linux Foundation CTO

arstechnica.com

19 points·ez77··3 comments

"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 He dismisses it as a rehash of outdated "1970s technology" and describes it as a conservative short-term solution.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.

The main point of ext4 (and ext3) is that they are backwards compatible; you can use your existing on-disk layout. Google probably has a zillion disks that they can't just reformat.

"Why is google moving to ext4?"

The Ars article says that ext2 can develop what amounts to fragmentation in the metadata, causing reading to slow down a lot as the file system is used. That matters for apps with heavy data turnover, like Gmail.

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