Re: fossil

Fossil must not fill up, however I would say that the dropoff was the lack of clear
documentation stating this.

Fossil has two modes of operation.

As a stand alone filesystem, not really intented (I believe) as a production
system, more as a replacement for kfs - for laptops or installation systems.

A full fossil system is when it is combined with a local venti (venti on the same
machine or on a fast, low latency network connection). Here most files are pulled
from venti (in the limit fossil only contains a single score which redirects the root
of the filesystem to a venti score. However as you change files the new version
is stored on fossil.

Every night aty 4 or 5 am (by convention) fossil does a snap, bumps it epoch which
marks all the changed files as readonly and further changes creates a new file.
The readonly files are then written to venti in the background and their space in fossil
reclaimed.

This means the fossil only needs to be big enough to contain all the changes you
are likely to make in a day - in reality 10Gb or fossil will never fill up unless
you decide to archive your entire dvd collection on the same day.
I have been running fossil and venti since 2004. Fossil did have problems doing
ephemerial dumps (short lived dumps every 15 mins which live for a few days).
This bug used to cause occasional fossil crashes but venti never lost a byte.

The bug was fixed before the labs froze and fossil has been solid since.

I used an ssd for venti which helps its performance, though even with this it will
never match liniux filesystem performance (cwfs may well do better), but I know it
and its fast enough for me for now.

-Steve