Reiser4 Implements Mirror & Failover Support

Edward Shishkin, one of the last remaining Reiser4 developers and the one who has been leading this out-of-tree file-system the past few years, has implemented logical volumes support with support for mirrors (in effect, RAID 0) and failover support at the file-system level.

Shishkin quietly announced on Sunday, "Reiser4 will support logical (compound) volumes. For now we have implemented the simplest ones - mirrors. As a supplement to existing checksums it will provide a failover - an important feature, which will reduce number of cases when your volume needs to be repaired by fsck."

With his lengthy mailing list post he covers the new functionality that is currently implemented within his branched version of the Reiser4 kernel driver and the user-space components for being able to create mirrors and failovers with this file-system.

Still on the TODO list of Edward is working on mirror tools, scrubbing, checksumming format super-block, and issuing discard requests for replicas on SSDs. There's still no signs of Reiser4 pursuing mainline Linux kernel integration so for now you'll be left to patch your stable kernel releases.