Lessfs now comes with a diesel Engine. As of release 1.4.0 it also supports Berkeley DB as backend for the meta data of the filesystem. Reason for adding support for Berkeley DB is not that it was sexy to introduce it. Nor that it was fun to write the code. I needed a very reliable back-end and speed was less important then reliability. While hamsterdb still looks promising, for now it does not fulfill the requirements.
Lessfs now waits until it recycles deleted data chunks in the ‘blockdata’ file. This is needed because the transactional databases may revert transactions to the last steady state when lessfs is shutdown uncleanly. If the actual data has been overwritten because of reusing deleted blocks then it would be possible that after reverting the transactions the filesystem would sustain data corruption. Lessfs now waits 10 * COMMIT_INTERVAL before the space of a deleted chunk of data is reused.
Please read the release notes if you want to upgrade from lessfs-1.x to this release.
If you want to try the Berkeley DB back-end then you can find additional information in: README.berkeleydb