Google, the giant search engine who knows a thing or two about speed, has decided to implement the ext4 as the filesystem for their servers.
In a post to the ext4 developer’s mailing list, Senior Engineer Michael Rubin explains that Google had been deciding upon a filesystem upgrade to their existing filesystem, and after a lot of performance testing of the available filesystems, including xfs, ext4 and jfs, they came to a conclusion that ext4 was best suited to their needs. Although xfs performed close to ext4, the deciding factor on ext4 was that it provided an easy upgrade path from their existing ext2 filesystem to ext4.
Ext4 has become the default filesystem for several of the popular Linux distributions including Ubuntu, Fedora and openSUSE and had become an official part of Linux kernel since Linux 2.6.28 kernel. ext4 features several improvements over its predecessor, amongst which include support for files upto 16 tebibytes ( 1 tebibytes equals 1,024 gibibyes , with 1gibibyte equal to 1.074 gigabytes) and a maximum volume size of upto 1 Exbibyte. Other features of the ext4 are backwards compatibility with ext2/ext3 filesystems, and a subdirectory limitation of upto 64,000 subdirectories, and an online defragmentation tool which is still under development stages, however.
Interestingly, one of ext4’s lead developer, Theodore Ts’o is also a Google employee, notes SJVN indicating that Google would most likely use his expertise in further getting even more performance out of an already fast filesystem.