Zumastor Linux Storage Project

You can read all about it in the Zumastor Howto. The current release is 0.7, which adds an experimental "revert to snapshot" feature, an experimental "multilayer replication" feature (e.g. for doing star topology software distribution), and lets downstream replicas retain snapshots (kind of important when using as part of a backup scheme).

Prebuilt Debian/Ubuntu packages are available at zumastor.org/downloads/releases.

Zumastor development is hosted at zumastor.googlecode.com.

• Subversion repository: code.google.com/p/zumastor/source
• Issue tracker: code.google.com/p/zumastor/issues/list
• IRC channel: irc://irc.oftc.net#zumastor
• IRC logs
• zumastor mailing list
• zumastor-commits mailing list
• Summer of Code ideas

Other documents

• Design Notes
• WIP slides and poster presented at FAST '08, 27 Feb 2008
• Zumastor Whitepaper - presented at SCaLE '07, 11 Feb 2007 (slides and audio recording here)
• Cluster Snapshots Block Device - Linux Kongress, 3 Sep 2004
• Cluster Snapshot Design - 8 May 2004
• Cluster RAID - Linux Kongress RAID 3.5, 27 Sep 2003

Kernel Patches

• Dan Phillips' bio throttling patch, part of how we prevent deadlock during memory pressure. See lkml discussion from 6 Dec 2007 and coverage at LWN.NET.
• Dan Phillips' PR_SET_MEMALLOC/PR_SET_LESS_THROTTLE patch, other part of how we prevent deadlock during memory pressure. (Any user app that's in the block writeout path needs to be written very carefully to avoid memory recursion deadlock; in particular, it should probably use mlockall, never allocate any memory while handling a write request (modulo a few KB of Heisenslop), and it should set PF_LESS_THROTTLE|PF_MEMALLOC using prctl, as provided for by this patch.) (Mixed in with the ddsnap stuff for now, sorry; ignore everything but the changes to include/linux/prctl.h and kernel/sys.c.)
• NFS suspend patch, part of how we make new snapshots available via the NFS server as they arrive from remote sites

Current contributors

Previous contributors

• Robert Nelson, Jane Chiu, Ross Combs, Alex Polvi, Chuan-kai Lin, Mark Roach, Frank Mayhar
• Phil Dibowitz - ddsnap SIGHUP handling patch
• Jonathan Van Eenwyk - ddloop deltafile mount patch (tarball includes a paper)