I ran dozens of file servers with only Fossil or both Fossil and Venti since 2004, and I never lost any byte of data.
I experienced only few problems with Fossil. Most of them caused Fossil to freeze or, more rarely, to crash. In most cases, I simply rebooted the file server, and it worked fine again. What I can say is: - these problems tend to appear far much often when running on virtual machines like Qemu, - running Fossil without Venti prevent some problems, like freezes during snapshot to Venti. I am currently running something like twenty file servers (including standalone machines), from 8GB to 1.5TB of storage. Most file servers are running Fossil with Venti, but some are only running Fossil. I mirror Venti through network and regularly backup arenas to DVDs (but I am recently moving to BD). So far, I only succeeded to reproduce data-lost problems on Fossil when running heavy stress testing. I can understand Fossil have problems and they might cause data corruption, but when data is archived to Venti, you can be sure it will stay forever. These problems with Fossil just have to be fixed. I am currently working on a fossil derivative which use libventi and libthread instead of liboventi and eventually fix these problems. I am already running it on some test file servers, but it's too early to talk about experiences with it. -- David du Colombier
