HAMMER

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HAMMER
Developer Matthew Dillon
Full name HAMMER
Introduced July 21, 2008 (DragonFly BSD 2.0)
Structures
Directory contents B-tree
Limits
Max volume size 1 EiB
Features
Supported operating systems DragonFly BSD

HAMMER is a high-availability 64-bit redundant clustering file system developed by Matthew Dillon for DragonFly BSD using B-trees. Its features include infinite snapshots, multi-master operation, configurable history retention and self-healing.[1] There is a stalled effort to port HAMMER to Linux.

Contents

[edit] Features

  • Keeps a full filesystem history, with settable pruning of old data.
  • CRC checksumming of metadata.[1]
  • Minimal remount time (no fsck required).
  • Designed for cluster mirroring and efficient remote access.
  • Support for very large file-systems (up to 1 exabyte).
  • Ability to re-optimize the layout in the background, on a live filesystem.

[edit] Limitations

Requires a pruning/reblocking cron job run a few minutes every night to incrementally clean up and regain space on the filesystem.

Does not yet support multi-master configuration.

[edit] Platforms

[edit] References

  1. ^ a b Wildner, Sascha. "HAMMER(5)". DragonFly On-Line Manual Pages. http://leaf.dragonflybsd.org/cgi/web-man?command=hammer&section=5. Retrieved April 3, 2009.  "After a non-graceful system shutdown, HAMMER file systems will be brought back into a fully coherent state when mounting the file system, usually within a few seconds."

[edit] See also

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[edit] External links

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