Introducing DualFS File System developers played with the idea of separation of meta-data from data in file systems for a while. The idea was lately revived by a small group of file system enthusiasts from Spain (from the little known University of Murcia) and it is called DualFS. We believe that the separation idea will bring to Linux file systems great value. We see DualFS as a next-generation journaling file system which has the same consistency guaranties as traditional journaling file systems but better performance characteristics. The new file system puts data and meta-data on different devices (usually, two partitions on the same disk or different disks), and manages them in very different ways: 1. DualFS has only one copy of every meta-data block. This copy is in the meta-data device, 2. The meta-data device is a log which is used by DualFS both to read and to write meta-data blocks. 3. DualFS avoids an extra copy of meta-data blocks, which allow DualFS to achieve higher performance than other journaling file systems. 4. DualFS implements performance enhancements: meta-data prefetch, on-line meta-data relocation and faster fsck and mkfs operations. 5. DualFS file system is suitable for use with TB and PB of storage We have carried out different experiments which compare DualFS and other popular Linux file systems, namely, Ext2, Ext3, XFS, JFS, and ReiserFS. The results, both performance and management, prove the value of the new file system design based on the separation of data and metadata which increase performance dramatically up to 97% by simply using an additional partition of same disk. We have performed extensive tests using micro-benchmarks as well as macro-benchmarks including Postmark v1.5, SpecWeb99, TPCC-uva. We also measured performance of maintenance tasks like mkfs and fsck which all show that DualFS performance is superior to all the other file systems tested with performance advantage in the range between 50-300% depending on the benchmark and the configuration. And all this performance advantage is a direct result of the separation of the meta-data and data. The project started in 2000 by Juan Piernas Canovas as the primary and almost unique contributor, with some small contributions by Toni Cortes, and Jose M. Garcia. The project was stopped for some time. We restarted the project last year, and after several months of updates and tests we created a SourceForge project with the intent to share the value of this old and yet new concept. The DualFS code, tools and performance papers are available at: <http://sourceforge.net/projects/dualfs> The code requires kernel patches to 2.4.19 (oldies but goodies) and a separate fsck code. The latest kernel we used it for is 2.6.11 and we hope with you help to port it to the latest Linux kernel. We will present the architecture, principles and performance characterization at the LFS07 next week. We are very interested to get your feedback and criticism. Sorin Faibish and Juan Piernas Canovas -------------------------------------- - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
