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AllocFS: A Filesystem With Allocations

Space allocation is a critical facility for making reliable data intensive computing systems. However, traditional operating systems do not make it easy to guarantee that space will be available for a future operation.

To address this limitation, we have developed AllocFS, a filesystem that allows users to make guaranteed space allocations within an existing directory structure. For example, the user simply issues mkalloc /dir/name 25M and receives a directory that is guaranteed to hold 25MB of data. Allocations are hierarchical, so this space can be further divided for other purposes.

AllocFS is a modified version of the production ext2 filesystem. It is a loadable kernel module that uses the same on-disk layout as ext2, so the allocation facility can be added to (or removed from) an existing filesystem without reformatting.

For more information, please read the user and installation manual. To ask questions or discuss technical details, please subscribe and post to the cctools mailing list.


  • AllocFS User Manual
  • allocfs-0.2-src.tar.gz
  • Getting Help with AllocFS
  • Publications

  • Operating System Support for Space Allocation in Grid Storage Systems, Douglas Thain, IEEE Conference on Grid Computing, September 2006.
  • Implementation Tradeoffs in Storage Allocation for Grid Computing, Douglas Thain, Technical Report 2006-04, Univ of Notre Dame, Computer Science and Engineering Dept, May 2006.
  • Separating Abstractions from Resources in a Tactical Storage System, Douglas Thain, Sander Klous, Justin Wozniak, Paul Brenner, Aaron Striegel, and Jesus Izaguirre, in Proceedings of IEEE/ACM Supercomputing, Nov 2005.
  • This research is supported by the National Science Foundation under grant CNS05-49087.