What You Need to Know for a Successful Subversion Migration
Migrating from Subversion (SVN) to Helix Core can seem like a daunting task. Will the migration disrupt development? What about the years of history?
With proper planning and testing, you can easily migrate from SVN to Helix Core quickly and without incident. And the benefits will be immediately evident: better workflow flexibility, scale, and performance.
Let’s explore some of the things you should include in your SVN migration toolkit:
- SVN Migration Planning
- SVN Migration Approaches
- Reevaluate Your Branching Strategy
- Subversion Migration Checklist
- Technical Tips for a Seamless SVN Migration
SVN Migration Planning
- Identify the key stakeholders for planning. Include IT and your version control system admin. And don’t forget daily users, like developers, managers, and product architects.
- What’s the current state of your SVN system? Document the version, server location, and any customizations. Run any data verification utilities. If you have corrupt data, it’s better to know about it upfront.
- Plan your new Helix Core deployment. Is your hardware sized appropriately? Do you have a good backup solution in place? If Helix Core will be on a new platform, how will you handle Unicode data?
- Document your current SVN configuration. Is your branching strategy a mess? Migration is a good time to fix that. Do you have in-house tools to support your users? Those may have to be ported to work with Helix Core.
- Consider key milestones. Is there a big release coming up that can’t be disrupted?
- Identify how much history to import. Will the latest file versions suffice or do you need detailed history?
- What tools and automation interact with SVN? Do you use a defect tracker or build runner integration?
- Plan your cutover strategy. Will your users transition to Helix Core at the same time or will you plan a phased approach?
- Determine what level of training your users and admins will need — online or classroom-based Helix Core training.
- How long will SVN be available after the migration? Should licenses be renewed? If so, for how long?
- Determine how you’ll measure migration success. Possibilities include verification of imported data, reproducibility of important builds, and a measure of impact on productivity.
SVN Migration Approaches
Determining what and how much history to import requires careful consideration. You may have different approaches for different products. This may depend on where they are in their lifecycle and importance to your organization.
Most former SVN customers never use the history they’ve imported. Figure out what you’ll really need before you take the time and effort required for imports.
There are three migration approaches you can consider: Tips Only, Detailed History Import (DHI), or Baseline and Branch Import (BBI).
This approach involves getting the latest file versions, or “tips,” from SVN and adding them to Helix Core. No history is preserved. This approach is sometimes appropriate for documentation but is rarely ideal for source code, except for prototype and demo code. This is, in essence, a “start over” approach.
Detailed History Import (DHI)
This is the most comprehensive conversion approach. It captures as much detailed branch/merge information as possible. This allows you to conduct historical research in the new system without requiring the old one. A DHI captures elements such as properties, user descriptions, and check-in comments. With this approach, you can see your old history in a new light with Helix Core’s powerful visualization tools. Depending on your plans, you may or may not need all information. Many customers will do a BBI first, and if needed, proceed with a DHI.
Baseline and Branch Import (BBI)
The BBI approach offers a lightweight migration alternative to the DHI. It’s more sophisticated than the Tips Only approach and avoids the technical complexity of a DHI. The BBI approach uses a branch diagram to select the history to import. The diagram shows the baselines, which are snapshots of a directory structure at a specified time, and major branching operations. It imports branching operations at a high level, capturing the sum of merge operations. A BBI lets you get started quickly and is very reliable.
Reevaluate Your Branching Strategy
You need to think about your branching process and what you want it to look like. How do you currently manage change flow in your product cycles? How do you want to implement and enforce codeline policy in Helix Core?
Helix Core has more powerful branching capabilities than SVN. You’ll want to ensure you leverage its advanced features and tools. This is an opportunity to improve and automate processes and decrease time-consuming daily merge operations.
Look at the Perforce Directory Standard template to help you plan your branching strategy.
Subversion Migration Checklist
Even though SVN migrations vary in complexity, all share similar milestones that must be met. Use this checklist to make sure you don’t miss key tasks during the migration.
Technical Tips for a Seamless SVN Migration
As you move from SVN to Helix Core, consider the following technical tips to help your migration go smoothly.
- Convert on the same platform as the server to prevent complications. After the migration, you can always change platforms.
- Migrations can be hardware intensive, so you may want a separate migration server. (This applies mostly for DHI migrations).
- Consider typemap, file types, and Unicode. Typemap is a Helix Core feature, so you’ll want to plan according to the data types you have.
- SVN has empty directories and Helix Core does not. Use .d or README files so these directories are no longer empty. Or, move the directories to your makefiles or build scripts.
- Use the flexibility of workspace mapping to handle SVN externals.
- Keep SVN as a point of reference.
Helix Core for Subversion Users: A Technical Guide to Learning Helix Core
This technical guide is based on years of field experience helping SVN customers transition to Helix Core. You’ll learn the main differences between Helix Core and SVN and how to adapt your development processes to leverage Helix Core’s full potential.
Former SVN Users Talk Migration
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