Clearcase migration to Git

[jbjonesjr]

From @nathos, my migration sherpa:

With regards to moving from ClearCase to Git, this deck from CollabNet is one of the best I've encountered. It has a couple of great slides that describe the fundamental differences. It also (softly) encourages folks to not bother attempting a history recreation in Git. Microsoft recommends the same approach.

I think the bigger challenge will be around build/release tooling, but our core functionality (Releases, etc.) and stable API help a lot here.

Where Git & GitHub are a dramatic impact for teams is the faster performance for even "simple" operations like status, commit, etc. At our Chicago Enterprise Summit last year, a former ClearCase admin couldn't stop singing GitHub's praises, as keeping ClearCase performant at scale is a challenge.

IBM DevWorks also published an article on their perspective on migrating from Clearcase to Git: doc
related doc: Git guide for Rational Team Concert users.pdf

cc/ @DaveEide for the latest and greatest on this topic

[jbjonesjr]

IBM's developed an RTC SCM tool extension to migrate an RTC repository into a Git repository:
https://github.com/rtcTo/rtc2gitcli

Inspired by rtc2git, but written in Java and hopefully faster. It is implemented as scm cli plugin.

A tool made for migrating code from an existing IBM's RTC SCM repository into a Git repository

https://github.com/rtcTo/rtc2git

[jbjonesjr]

One of the problems with rational, clearcase, and associated tooling is these are capabilities that don’t quite have analogues in Git (file merges, etc).

In general, constructing a history of releases may be a healthier approach, but it depends a lot on how they’ve each team has used RTC historically.

GitHub Services Engaged a customer on 03-28-2017 to migrate them rtc-jazz to GitHub. Internal to GitHub they have good notes on how that went in github/services/engagements.

[jbjonesjr]

https://therub.org/2013/07/19/clearcase-to-git/