Posts Tagged ‘ Source Control ’

VSS to SVN Migration


This post has a few tips and insights from my recent experience of migrating from VSS to Subversion.

The first thing to note is that version control in SVN has some conceptual differences to VSS and it is worth spending some time reading the SVN Book to understand these differences. Understanding these differences will often give you the ‘why’ for migrating to SVN.

Why did we migrate?

Our shortlist of reasons for migrating:

  1. Branching in SVN is much easier than VSS.
  2. VSS doesn’t always play nicely when disconnected (issues with working folders)
  3. With SVN I can work on n individual bugs in completely separate folders, allowing me to easily work on the bugs independantly (useful for example if you are say writing a new feature against the dev source and urgently need to fix a bug in the production source). Once again VSS has ‘working folder’ issues when you work this way.
  4. Depending on where you store your repository, SVN plays nicely over the internet…fantastic for teams working remotely.


If you can migrate without keeping the history then that is the easiest and fastest way.It’s not ideal but you can always still get the history of a file from VSS.

Note:  easiest != best.

If you want to maintain history I used this migration tool with great success.

A few things about the migration tool…

  1. Play with it on a mini repository first! (and remember it changes your system clock!)
  2. The most time consuming part of the process is when it does a ‘get history’ from VSS. Drove me nuts because you get the history with the VSS gui and you get the results almost immediately, get the history from the cmd line and it took 40-60 seconds! I did search for some cmd line switch to help but no joy.
  3. It’s c++ so I was too scared to make any changes and it worked fine but the source is available if you need to tweak it.
  4. I had some corruptions in VSS, this causes the migration tool to pause. Make a note of the file, ignore and continue.
  5. Depending on the size of your repo you may want to import from a logical sub project.

You will also need to do the migration on a separate dedicated machine because it changes the system clock when committing. So yes the migration tool must run on the same box as the repository it is committing to. Once the migration is complete you can either copy your flashy new SVN repo to it’s new ‘production’ home or if you have set it up with a Berkely DB then you’ll need to export and import. The SVN Book has plenty of details on ‘how’ to export/import etc.

This blog entry helped me as well.

When You are Done


I strongly recommend you run the app through a full test phase once you are done to ensure you ‘got everything’.

Point to the New Location

If you have a CI server setup you’ll need to configure to point to the new repo, same goes for you and your team members.

Maybe change the location of the old VSS repo so that no one accidentally checks in. Don’t delete it though.

VSS File Date on Get Latest

VSS has many settings, most of which most of us leave set at the default.

One of the few settings I think should be changed is the local file date. Why?

The default setting is Current. This means that when you do a get latest the Date Modified shown in windows explorer for the file will be the current time. Knowing the time that you last got the latest version isn’t very useful information, it is much more useful to know when the file was actually last changed.

So to ensure you get that info just change the setting shown below to Modification and from now on when you do a get latest it will always be the date the file was last modified.

Much more useful 🙂

Making the Change

Open VSS and go to ->Tools-> Options

Change ‘Set Date/time on local files’ from Current to Modification:-