The filesystem used in the vast majority of Linux (and to a lesser extent on other Unix) distributions is the ext3 filesystem, which stands for extended filesystem. Slashdot recently pointed to an article on IBM DeveloperWorks discussing the new ext4 filesystem currently in development, and some of its new features. So what is a filesystem really?

Over the weekend, I converted my laptop to use the ext4 filesystem. So far so good! So far I’ve found one bug as a result of my using ext4 in production (if delayed allocation is enabled, i_blocks doesn’t get updated until the block allocation takes place, so files can appear to have 0k blocksize right after they are created, which is confusing/unfortunate), but nothing super serious yet.

ZFS is an advanced filesystem created by Sun Microsystems but not supported in the Linux kernel. The ZFS_on_FUSE project allows you to use ZFS through the Linux kernel as a FUSE filesystem. This means that a ZFS filesystem will be accessible just like any other filesystem the Linux kernel lets you use.

"The Linux filesystem is a complex and the first thing that most new users shifting from Windows will find confusing is navigating the Linux filesystem. The second thing is that not too many people are familiar with how the filesystem works or know how to troubleshoot if any problems arise."

HP has released Digital's Tru64 Advanced Filesystem under the GPL, free for Linux developers to borrow. And developers can learn a lot from this museum piece.

With MySQLfs you can store a filesystem inside a MySQL relational database. MySQLfs breaks up the byte content of files that you store in its filesystem into tuples in the database, which allows you to store large files in the filesystem without requiring the database to support extremely large BLOB fields. With MySQLfs you can throw a filesystem into a MySQL database and take advantage of whatever database backup, clustering, and replication setup you have to protect your MySQLfs filesystem.

This article gives you a jumpstart on performing benchmark on filesystem using iozone a free Filesystem Benchmark utility.

eCryptfs is a kernel-native crypographic filesystem. It's also a stacked filesystem, eCryptfs must work on top of another filesystem such as Ext3. This means that you don't need to allocate space for eCryptfs, it will grow and shrink as you add files to it.

Over time, a filesystem accumulates a lot of useless items. FSlint is a nifty little tool that helps you clean your filesystem by pointing out junk in the form of empty directories, corrupt symlinks, files with bad names, duplicate and temp files, and more.