I certinaly had problems a few years ago with fossil deadlocking, since I disabled ephemeral snapshots it has been quite reliable.
My feeling (nothing more than that) was that the deadlocks seemed to occur when I receved email just at the time of the snapshot. the problem seemed to occur at a rate of once per month or two for my lightly loaded home server. I did try to run two file servers for a while, exporting /proc from the test machine with snapshots enabled to a seccond one. The hope was that I would be able to use acid to debug the test machine's fossil when the problem occured. Sadly I never caught the problem and had to decomission the old machine (house repairs). -Steve
