What's the best way to migrate from SourceSafe to ClearCase?

Question

We currently have a fat SourceSafe DB with ten years of code in it. We\'re looking for an easy and stable way to import all of this in to a new Clearcase/Jazz environment.

Answer 1

In theory, clearexport_ssafe is the right tool:

The clearexport_ssafe utility reads the files and sub-projects in your Microsoft® Visual SourceSafe current project and generates a data file, which clearimport uses to create equivalent VOB elements.

By default clearexport_ssafe exports the files and subprojects in the Visual SourceSafe current project, but it does not export any files contained in subprojects. To export all files in all subprojects, specify the –r option.

In practice, the migrations I made (not from VSS though) involved the import of a few recent labels, and then the HEAD, into ClearCase.

That means the main tool I use for any import (from any other VCS) is clearfsimport.
You may loose some meta-data (like the author of a version, and labels), but at least it is source-agnostic, and since your massive import only concern an handfull of labels from the source, you end up quickly with an operational VOB.

Answer 2

I actually lived through a VSS to Clear Case conversion. Rational had a conversion tool that we ran. It took FOREVER (2-3 days, but see below) to complete on our VSS database of maybe 2 years (maybe it was 3 years, but not close to your 10 years). But it worked far as I recall. It maintained the history and labels.

The slowness problem was likely due to a flaky RAID controller in our new source control server. The imports worked fine, but Clear Case would detect corruptions in it's data after a few days of working (often after a label). After several re-imports, firmware updates, and a new server it all worked out.

I'd still plan to give the import a weekend to run. Try to get someone who can remote in occasionally to check it's progress.

On a side note, I've also done VSS conversions to Perforce and TFS. In general, I suggest giving the import tools a try. If they work, great. If they give you grief, just do what everyone else answering is suggesting: just start over by adding all the files as new.

Answer 3

I know this doesn't answer your question directly, but we had a similar problem several years ago when we moved from VSS to Perforce. We looked at the ways in which we could migrate the histories for all the files, but any solution we found had problems and would have taken a long time to execute.

In the end we simply decided to import the current version of the code into Perforce as the baseline and leave the old history in VSS. In the early days we did refer back to VSS occasionally, but after a few months we didn't need to.

If there's a problem with a file you only need the last couple of revisions to be able to see what's changed and why. So if the file changes fairly frequently you'll soon build up a useful history in the new repository. If the file doesn't change then by definition it's stable an you don't need the history.

If you back up the old repository you can always go back to it if you really need to to dig out the hold history.

Answer 4

I'd take the most significant labels and import them into ClearCase by 'clearfsimport'.

Answer 5

From IBM's web site:

http://www-01.ibm.com/support/docview.wss?ratlid=cctocbody&rs=984&uid=swg21222507

and this:

http://www.cmcrossroads.com/component/option,com_fireboard/func,view/id,63051/catid,31/Itemid,593/

However, ChrisF's answer is the same that I would suggest.

The effort involved generally is not worth it given the "benefit" of migrating the history.

I would just take snapshots of the current "tips" of the branches and put those under your new version control system.

I went through this exercise at least 3 times in my career. One conversion to Perforce and two to SVN.

I think I recall that we did some partial history imports, but then just dropped it all as the information we needed was in some other form. The actual repository history of changes just wasn't important enough to go through the pain. We did keep the database around for a year or so in case anyone wanted to look. I don't recall anyone complaining about it.

(I'm also curious why anyone would choose ClearCase over the rest of the ones out there - my guess is for integration with other Rational/IBM stuff)

EDIT

I would ask ClearCase/IBM. They'll have the best up to date information.