1999 Linux Symposium

the extended 3 filesystem


The Extended 3 Filesystem

The ext3 filesystem is a journaling extension to the standard ext2 filesystem on Linux. Journaling results in massively reduced time spent recovering a filesystem after a crash, and is therefore in high demand in environments where high availability is important, not only to improve recovery times on single machines but also to allow a crashed machine's filesystem to be recovered on another machine when we have a cluster of nodes with a shared disk.

This talk will describe the ext3 filesystem, both its design goals and its implementation. It will explain some of the challenges involved in adding journaling in a way which is completely compatible with existing ext2 filesystems (it is possible to migrate existing ext2 filesystems to ext3 and back again), and will cover the architecture of the implementation, which involves a completely new, generic block device journaling layer in the kernel.

Dr. Stephen Tweedie

Stephen has been involved with the development of the Linux kernel since its early days. His work has been primarily on the filesystem and virtual memory code, with miscellaneous contributions all over the kernel. However he never goes near the network code. His recent and current projects include several high-end features such as raw IO, fast zero-copy filesystem IO and high availability.

Working for DEC for two years, Stephen worked on VMS kernel internals for high-availability clustered filesystems. He is now employed full-time by Red Hat, which lets him work on Linux exclusively.

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