How to migrate SVN large size repository 1 4TB into GIT

Question

Migrating a large SVN repository (around 1.4TB) to Git can be complex and challenging due to the size and data involved. Such a migration requires careful planning to preserve history, maintain data integrity, and handle large volumes of data efficiently. You need to choose the right tools and strategies, such as breaking down the migration into smaller parts or using specialized migration tools that can handle big data sizes. Additionally, it’s essential to consider the hardware requirements, potential cleanup before migration, and testing afterward to ensure accuracy and completeness.

Answer 1

A large SVN repository like ~1.4TB is a stressful migration task that requires a strategic and planned approach mainly due to its size and potential complexity. The following is a step-by-step toward the migration:

1.Preparation

Audit the SVN repository: Understand your structure, branches, tags, and history. Identify unnecessary data (e.g., obsolete branches) that you can exclude from migration in order to reduce size.

Clean up: Where possible, clean up large binary files or unused data from the SVN repository, as this helps optimize the size of the migration.

2. Choose the Right Tools

git-svn: It's a built-in command that loads SVN history into Git. This is suitable for smaller repos, but given your large repository size, it might not be efficient.

SubGit is more powerful and suitable for larger repositories with full history and incremental sync between SVN and Git. This would be more suitable for this size of repository

svn2git is another tool, but it can face some issues with extremely large sizes so tread carefully.

3. Optimization of Process

Incremental Migration: Rather than having everything at one go, broken migration splits the repository into smaller chunks, such as individual branches, so as not to overload the system during the migration process.

Branching strategy: First, only key branches, such as the trunk, important tags, and active feature branches, should be migrated, while other less important branches are incrementally brought along if needed.

4. Run the Migration

For massive repositories, migrate the repository overnight or off-peak. Use the chosen tool, such as SubGit, to make the migration.

5. Large Files

Use Git LFS for large files to manage the binaries efficiently so that Git does not slow down due to large objects

6. Validation post-migration

Test the migrated Git repository thoroughly to ensure that all the data, branches, and commits are sound.

Compare random commits between SVN and Git to ensure the correctness of your migration.

7. Finalize the Migration and Shut Down SVN

After thorough testing, switch to Git as the version control system. Then, let your team members know to shift all their local SVN workspaces to Git.

Once you are satisfied that it has migrated properly, you may decommission the SVN repository.

Best Practice

Backup SVN repository: Make a good backup of your SVN repository before you start.

Communicate to the team: Be transparent and keep all stakeholders involved. Ensure proper documentation for the team about how to use the new Git repository.

This method ensures a smooth and efficient migration of large SVN repositories to Git with significantly cut risks and downtime.

Answer 2

When migrating a large SVN repository (~1.4TB) to Git, size, complexity, and integrity must all be considered in a methodical and well-planned manner. Here's a different strategy:

1. Analysis Prior to Migration
Audit of the Repository: Examine the history, branches, tags, and structure to determine what is most important.
Remove Duplicate Information: Ignore big binary files unrelated to current work, unused tags, and out-of-date branches. This eliminates superfluous mass.
Getting the team ready: Notify all parties involved of the migration schedule and how it may affect workflows.
2. Pick the Appropriate Migration Instrument
Large repositories with history and bidirectional synchronization during migration are best suited for SubGit.
Git-svn: Ideal for incremental migrations or smaller repositories.
Custom Scripts: For really specific needs or unusual repository configurations.
3. The Strategy of Incremental Migration
Prioritize the migration of vital branches, such as the trunk and active development branches.
To cut down on processing time and errors, use a chunked migration approach for large repositories, moving particular subsets (such tags or historical data) independently.
4. Carry Out the Migration
First Configuration: In order to receive the migrated data, create a temporary Git repository.
Configuring the Tool: Adjust your migration tool (like SubGit) to fit your tagging and branching scheme.
Off-Peak Performance: To reduce interruption, carry out the relocation during off-peak hours.
5. Handle Big Files
Transfer big binary files to Git LFS (Large File Storage) for better administration and to avoid Git performance issues.
6. Quality Checks and Validation
Verify branches, commits, and tags by contrasting SVN with Git data.
To make sure the migrated repository is complete and intact, run thorough tests.
7. Finalization and Cutover
Once the new repository has been verified, move your team to Git workflows.
Update CI/CD pipelines and development tools to work with Git.
The SVN repository should be decommissioned after all workflows and systems have stabilized.
Top Techniques
First, backup: Before you begin, make a full backup of the SVN repository.
Record and Communicate: Make sure your migration documentation is clear, and teach team members how to use Git.
Keep an eye out for problems: After the transfer, keep an eye out for any usability or performance problems with the new Git repository.
Even the biggest SVN repositories can smoothly migrate to Git thanks to this methodical and staged strategy, which also reduces risks and guarantees data integrity.
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