monotone

There's a plethora of SCM software out there. Ever since the subversion guys tried to supplant CVS (because quite frankly, CVS needed fixing), SCMs have become the new mail client/editor, i.e. "software you must have written yourself at some point".

Then Tom Lord brought arch onto the scene, and introduced the revolutionary idea that SCMs should not follow a centralized, but a distributed model (apologies if my chronology is wrong here, this is how I experienced the development). Except for a few arch spin-offs, not much happened for a while.

A few years later, though, suddenly distributed SCMs were the thing to do. Since then we've seen monotone, git, bazaar, mercurial and svk rise in popularity.

Since a distributed SCM was what I needed, and wanted since arch, I tried them all at some point... and stuck with monotone.

Now I should mention that when I decided to stick with monotone, git and mercurial weren't around yet. Compared to the others, though, monotone shines on the following points:

stability
not trashing my repository
speed
documentation
clear development vision/design
code structure/clarity
friendly developer community
userfriendliness
upgrade-path from earlier versions
not trashing my repository (yes, it's important)

I primarily reviewed git and mercurial because they could, in theory, improve upon monotone. What put me off the former is that it's really a fairly loose collection of tools, written in multiple languages, and without any coherence between them.

Mercurial on the other hand looks fairly cleanly designed - but it's slower than monotone, and doesn't add anything I need.

In the end, by these criteria, monotone is simply the best SCM I've tried so far. That's not to say it's entirely free of warts, of course, but they're easily dealt with.

All that's left to say is this: try it for yourself!

Each day I travel to and from my workplace on a bus for some 35 minutes: thanks to monotone and its distributed nature I can not only hack at code on my laptop in that time, but also commit changes, diff and annotate and do everything with any past revision of the software I'm hacking at.
Everyone can work in a completely local way, needing only to sync to each other; there is not even need for a "central" server, only one (or more) places where people agree to exchange data, but if that goes offline, every single use has got it all, and can create a working mirror with the use of a single command.
The authors have always chosen the safest approach to data, every single commit is digitally signed, everything is mirrored on every node, everything is secure to the point that even in the first months of development many data-content problems turned out to be actual HDD failures and not problems in monotone.
I love this software.