Zumastor as an alternative for LVM/DRBD?
While reading Colin's post about LugRadio Live, I stumbled over the Zumastor Linux Storage Project. Going through the project home page and their HOWTO got me curious - could this eventually become an alternative to using DRBD (for replicating data) and LVM snapshots (for performing backups)?
Zumastor is Free software that adds enterprise storage features (primarily improved snapshots and remote replication) to Linux.
Snapshots
LVM already lets administrators create snapshots, but its design has the surprising property that every block you change on the original volume consumes one block for each snapshot. The resulting speed and space penalty usually makes the use of more than one or two snapshots at a time impractical.
Zumastor keeps all snapshots for a particular volume in a common snapshot store, and shares blocks the way one would expect. Thus making a change to one block of a file in the original volume only uses one block in the snapshot store no matter how many snapshots you have.
Replication
Andrew Tridgell's rsync is a wonderful tool for replicating files remotely. However, when doing periodic replication of large numbers of infrequently changing files, the overhead for figuring out what files need to be sent can be extreme.
Zumastor keeps track of which block change between one snapshot and the next, and can easily send just the changed blocks. Thus Zumastor can do frequent replication of large filesystems much more efficiently than rsync can.
I assume it's not ready for production use yet, but it would sure be interesting to investigate on how to utilize it for the purpose of running MySQL on top of it...
I will keep an eye on this project, I wonder if I will have to add support for Zumastor snapshots to mylvmbackup at some point? 
