[eterm]

It may well be the reason. I don't know the parent commenter but speaking from my own experience I recently tried to migrate a legacy code base from svn to git and the common tools all failed for me. One of them ran for ~72 hours before falling over for "reasons".

That was only ~6 years of commit history too. I could imagine 30 years is a whole extra logistical challenge. Not to mention making sure the whole developer base is aware of the change, prepared for it and willing to either update documentation where it refers to revision numbers or write some instructions on how to find a new commit reference from an old revision number.

The tag model is also different between svn and git.

It's not out of ignorance that the switch can be difficult, we've had some projects on git for years and we're comfortable with it.

Just because you've switched easily from svn to git doesn't mean everyone has the same experience.

[thewebcount]

Same. We have a 20 year old code base we migrated from Perforce to svn about 10 years ago. Now they want to migrate to git. Unfortunately, we can't get it to work either. Same thing - after many hours of running it just fails with typical useless git messages that nobody comprehends. It's quite frustrating.

(And personally, I hate git. I've used it professionally, and while it works, it's very difficult to use compared to svn or p4. Between it's utterly incomprehensible made-up terminology and horrid syntax, and hashes for commit numbers instead of just an incrementing integer, it's quite a bit less useful than svn was for us. But it's being forced on us, unfortunately.)