There never seems to be a good time to change tools. There will always be releases to make, builds to test, critical patches to issue, and it's understandably hard to justify even the smallest amount of downtime in such real, customer-facing activity. Indeed, when there's lots of this real work to be done it's equally hard to dedicate the time to take proper care when executing such a tool change.

On the other hand, by taking such an argument to the extreme, software developers end up stuck using Visual Studio 6.0 and grumbling (unfairly) about Microsoft's poor support for C++.

We were, then, keen to proceed. Our transition plan was simple. The timescale was short but manageable—and we knew that if we missed the slot, we wouldn't get another chance for a while.

As part of the evaluation, we'd created some backup scripts to mirror a Subversion repository to our backup machine. Next, we set up a migration script to:

So, to initiate the transition, all we had to do was schedule the migration script to run overnight. In the morning, if the log files were clean, we could kick off the Subversion backups, point the Subversion server at the newly imported repository and start it up, restart the CVS server in readonly mode, and we'd be done.