SVN to Git Migration Guide

What you will learn

• Understand the core purpose of SVN to Git Migration Guide
• Master the basic usage and common options of SVN to Git Migration Guide
• A complete guide to migrating from Subversion (SVN) to Git, covering history conversion, branch mapping, team training, and common pitfalls.
• Understand key concepts: Before Migration
• Know when to use this feature and when to avoid it

Start with a problem

Your team is migrating from another version control system to Git, or moving code and history between different Git platforms. You're worried about losing commit history or author information during the process.

One-Sentence Understanding

Migrating from SVN to Git is not just copying code — it's shifting from "centralized file versioning" to "distributed snapshot engine" thinking.

Before Migration

Assess the SVN Repo

svn log -q --limit 1
svn ls ^/

# Confirm standard layout
svn ls ^/trunk
svn ls ^/branches
svn ls ^/tags

Prepare Author Mapping

Create authors.txt:

svn_username = Full Name <email@example.com>
jdoe = John Doe <john@example.com>

Tool Selection

Migrate with git svn

Step 1: Clone

git svn clone http://svn.example.com/project \
  --stdlayout \
  --authors-file=authors.txt \
  --prefix=svn/ \
  project-git

cd project-git

Step 2: Clean Up Tags

git for-each-ref --format='%(refname)' refs/remotes/svn/tags/ |
while read tag; do
  tag_name=${tag#refs/remotes/svn/tags/}
  git tag "$tag_name" "$tag^{}"
  git branch -r -d "svn/tags/$tag_name"
done

Step 3: Map Branches

git for-each-ref --format='%(refname)' refs/remotes/svn/ |
  grep -v 'svn/tags' |
while read branch; do
  branch_name=${branch#refs/remotes/svn/}
  git branch "$branch_name" "$branch"
  git branch -r -d "svn/$branch_name"
done

Step 4: Push to Remote

git remote add origin git@github.com:user/project.git
git push origin --all
git push origin --tags

Common Issues

Large Files

# Find large files
git rev-list --objects --all | git cat-file --batch-check='%(objecttype) %(objectsize) %(rest)' | sort -k2 -n -r | head -20

# Clean with BFG
java -jar bfg.jar --strip-blobs-bigger-than 100M project.git

Empty Directories

find . -type d -empty -not -path "./.git/*" -exec touch {}/.gitkeep \;

Binary Files

Use Git LFS:

git lfs install
git lfs track "*.dll"
git lfs migrate import --include="*.dll,*.exe" --everything

Team Migration Plan

Phase 1: Assessment

1. Evaluate SVN repo (history, size, branches)
2. Prepare author mapping
3. Choose migration tool
4. Trial migration off-hours

Phase 2: Pilot

1. Small team tests Git
2. Collect feedback
3. Improve documentation

Phase 3: Switchover

1. Freeze SVN
2. Final migration
3. Verify results
4. Full team switch

Phase 4: Transition

1. SVN read-only (1-3 months)
2. Train team on Git workflows
3. Archive SVN repo

Mindset Comparison

Try it yourself

1. Practice the svn-to-git command in a test repository and observe state changes before and after
2. Experiment with different options and compare the output differences
3. Simulate a real scenario where you would need to use this, and walk through the full process

Continue Learning

1. learning-path/quick-start — Git quick start
2. workflows/feature-branch-collaboration — Feature branch workflow
3. best-practices/commit-hygiene — Commit conventions

Further reading

Keep going on the same topic:

• Repository Migration Strategy Guide
• Cross-Platform Git Migration