A ClearCase migration can be a daunting task. Will the migration disrupt development? What about the years of history?
Luckily, you can migrate from ClearCase to P4 — version control from Perforce — without disruption and without losing years of history.
In fact, with proper planning and testing, you can make your ClearCase migration easy. 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 ClearCase migration toolkit:
- Why Migrate From ClearCase to P4?
- How to Plan a ClearCase Migration
- Three ClearCase Migration Approaches
- Your ClearCase Migration Checklist
- Kick Off Your ClearCase Migration
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Why Migrate From ClearCase to P4?
There was a time when ClearCase was on the cutting edge of technology. Today, ClearCase just doesn't cut it.
Still Using ClearCase? Consider...
- How many admins do you need to manage ClearCase?
- Does UCM make ClearCase easier to use or more restrictive?
- Does ClearCase scale enough for your team?
- Do you have the budget and tolerance to keep managing MultiSite?
Teams That Migrate From ClearCase to P4 Find…
- Admin work is easier.
- Development is faster.
- Licenses are less expensive.
- Security needs are met.
Why 3 Teams Migrated...
“Perforce is the best all-round solution for us. We estimate that Rational ClearCase currently costs us around $500,000 per annum to run, whereas we predict that Perforce will be nearer $150,000.”
From a Fortune 100 global investment bank
“Perforce is one of the most important software applications in use at National Instruments today. With so many different groups relying on Perforce, we really appreciate the flexibility of the system."
"From a developer productivity perspective, there is absolutely no comparison. Merge or integration tasks that would take days to complete in ClearCase — and often involve multiple people — are now done in hours.”
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How to Plan a ClearCase Migration
Migration projects from ClearCase to P4 vary greatly in scale and complexity.
Small, simple environments with basic migration requirements are typically migrated in about 8 business days. This includes setting up P4, migrating, and training users and administrators.
Large, complex ClearCase environments may perform a series of migrations over the course of several months (or more), as teams migrate at times convenient for them.
Here's how to plan your ClearCase migration.
1. Identify Your Stakeholders
Include IT and your version control system admin. And don’t forget daily users, like developers, managers, and product architects.
2. Assess the Current State of Your 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.
3. Plan Your New P4 Deployment
Is your hardware sized appropriately? Do you have a good backup solution in place? If P4 will be on a new platform, how will you handle Unicode data?
4. Document Your Current ClearCase 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 P4.
5. Consider Key Milestones
Is there a big release coming up that can’t be disrupted?
6. Identify How Much History to Import
Will the latest file versions suffice or do you need detailed history?
7. Evaluate Integrations
What tools and automation interact with ClearCase? Do you use a defect tracker or build runner integration?
8. Plan Your Cutover Strategy
Will your users transition to P4 at the same time or will you plan a phased approach?
9. Determine Training Required
Determine what level of training your users and admins will need — online or classroom-based P4 training.
10. Consider Retaining ClearCase
How long will ClearCase be available after the migration? Should licenses be renewed? If so, for how long?
11. Decide on Success Metrics
Possibilities include verification of imported data, reproducibility of important builds, and a measure of impact on productivity.
Back to topIBM ClearCase to P4 Migration Guide
This technical guide is based on years of field experience helping ClearCase customers transition to P4. You’ll learn the main differences between P4 and ClearCase. And you'll learn how to adapt your development processes to leverage P4’s full potential.
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Three ClearCase 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.
There are 3 migration approaches you can consider: Tips Only, Detailed History Import (DHI), or Baseline and Branch Import (BBI).
Here, we give a quick overview of the approaches. You can get a more comprehensive overview in our migration guide.
Start Over (Tips Only)
This approach involves getting the latest file versions, or “tips,” from ClearCase and adding them to P4. 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.
Starting over offers some benefits. First, it can be easy. You define target directories in P4, and then add the files. Because there is less to migrate, it is also faster.
Do a 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.
Perforce has a sophisticated tool and process that enables conversion of very detailed historical data from ClearCase to P4. The tool has been successfully used for performing detailed history conversions from fairly large ClearCase data sets (about 100 GB) to P4.
With this approach, you can see your old history in a new light with P4’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.
Use a 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.
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Your ClearCase Migration Checklist
Even though ClearCase migrations vary in complexity, all share similar milestones that must be met. Use the ClearCase migration checklist to make sure you don’t miss key tasks during the migration.
1. Evaluate ClearCase
- Assess ClearCase usage.
- Check out tools, processes, and infrastructure.
- Consider user interactions.
- Define your migration requirements.
2. Determine a Branching Strategy
- Review your existing branching strategy.
- Consider Perforce Streams.
3. Map Your New System
- Plan your directory structure.
- Define release processes and standards.
- Select a data conversation strategy.
4. Secure Your Property
- Address intellectual property concerns.
5. Build Your Adopters
- Establish a transition team.
- Contact professionals.
- Schedule training.
6. Cut Over to P4
- Select your first project.
- Review the first project.
The Professional Services team at Perforce has extensive experience migrating complex ClearCare environments to P4. They can ensure your migration goes smoothly.
Get the Checklist
Want to download a complete copy of the checklist for later —
including extra tips?
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Kick Off Your ClearCase Migration
Ready to make the switch from ClearCase to P4? You can try P4 out for up to 5 users and 20 workspaces for free. And once you decide P4 is right for you, we can help you roll it out to the rest of your team — and kick off your migration.