October 28, 2019

ClearCase vs. Git: Which VCS Is Better?

Git at Scale

What’s the difference between ClearCase and Git? There are a lot of major differences (and very few similarities). Here, we cover the most important ones.

Read along or jump ahead to the section that interests you the most.

➡️ Easily Switch From ClearCase to Helix Core

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What ClearCase and Git Have in Common

Both ClearCase and Git are used for version control. And both have the ability to branch and merge. But that’s where the similarities end.

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ClearCase vs. Git: 7 Key Differences

ClearCase and Git are entirely different breeds of version control. There are 7 key differences you’ll need to consider when choosing between them.

1. Architecture

Architecture is the biggest difference between ClearCase and Git. ClearCase is centralized while Git is distributed.

ClearCase has a file-based architecture (where everything happens at the file level). And Git has a hash-based architecture (where everything happens at the branch level).

In ClearCase, you need to apply metadata (e.g., tags) for every file — one at a time. That’s all well and good — if you have 10 files. But when you have 100K or more files, applying those tags manually just doesn’t fly. You’ll need to create an entry for every single file. If someone tries to pull all files with that tag while you’re still tagging, it can break builds and wreak havoc.

The same work of creating a label in Git might only take a second. 

Which One Has Better Performance?

It depends on who you ask.

Git has better performance at an end user level. Developers like the distributed and decentralized nature of Git, where everyone can clone from everyone. And they can do their work without being connected (including diffs, merges, rebases, etc.).

However, Git’s architecture creates problems at an enterprise level. Enterprises need a single source of truth. Git can’t provide that (unless you add tools, e.g. Helix TeamHub, Bitbucket, GitHub, or GitLab).

ClearCase can provide a source of truth at an enterprise level. However, it creates performance bottlenecks and can break builds. It was built for an era of 1,000s of files. Not an era with 100K to millions of files. And the larger the number of assets, the slower the system.

There’s a lot of work required to view a single file. And ClearCase is also network-intensive.

2. Repository Design

Repository design is another area of division for ClearCase and Git.

ClearCase repositories are Versioned Object Bases (VOBs). While a team might have multiple large VOBs, they’re all considered part of a monolithic codebase. The same volume of files (typically used in ClearCase) would require exponentially many repositories in Git.

This difference in repository design is related to a bigger version control issue. Is it better to have a monorepo or multiple repos?

There are a lot of benefits to using a monorepo. For starters, a monorepo provides a single source of truth for your team. This makes it easier to share and reuse code — and collaborate across teams. It also simplifies dependency management. Plus, you’ll be able to make atomic changes across the whole project.

Multiple repositories are most often used if you need to break up files based on type of file or team. By componentizing your repositories, it helps you solve some scalability issues. But you’ll still struggle to stitch everything back together and get a single source of truth. And you won’t be able to atomically submit changes.

Which Design Scales Better?

ClearCase’s repository design scales better than Git’s. That’s because a monolithic repository is simpler, clearer, and atomic.

Splitting Git into multiple repositories might make it easier to manage the individual pieces. But it’s more difficult to manage the whole project.

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Scale and Still Work With Git

It’s time to switch to a better version control. One that scales. One that’s fast. One that gives you the automation, flexibility, and control you need for branching. One that works with Git. 

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3. Branching and Merging

Git and ClearCase have major differences in branching and merging.

Git offers lightweight branching, which can be faster. ClearCase, on the other hand, offers more granular merging.

Git branching is an instantaneous process. You merge from branch to branch.

ClearCase branching is done on a per-file basis. When merging from branch to branch, you still merge on a per-file basis.

Both Git and ClearCase have good merge algorithms.

Which Branching/Merging Model Is More Efficient?

Git’s lightweight branching is more efficient.

But there are still issues with the Git branching model, particularly if you’re working in a large repo. For instance, if you have 100 files that are different, you need to merge all 100 of those files. You can’t just merge a couple of files and be done.

ClearCase branching involves a lot of manual effort. It’s time-consuming. And it makes working on private/task/feature branches more painful for ClearCase developers. On the other hand…

ClearCase merging is more efficient.

In ClearCase, you can do a merge preview. And then you can divvy up the work and merge by file. However, merge conflicts can be time-consuming in ClearCase.

Git merges can run into some issues, particularly if you have multiple teams working in the same repository. You wouldn’t be able to divvy up the work, like with ClearCase. For instance, if you have different assets in Git repos — e.g., PHP code and C++ code — a PHP developer could be asked to merge C++ code.

4. Replication Model

The replication model is another important factor to consider with ClearCase vs. Git.

ClearCase offers a separate product for replication, at an additional cost — ClearCase MultiSite. Git doesn’t have a replication model — you’ll need to add a product such as Helix4Git, Gerrit, or GitLab Geo.

Replication is an absolute necessity for teams with remote users. It allows them to experience local performance, despite being remote.

Which Replication Model Is Better?

There are issues with both replication models.

ClearCase Multisite is an expensive add-on. If you replicate a repository for the one person across the globe who needs it, you’ll have to pay for everyone who touches it (even if you have 100s of developers locally). Managing and maintaining ClearCase MultiSite can be a nightmare, too.

Git, on the other hand, doesn’t have a native replication system. So, you have to choose between products such as Helix4Git, Gerrit, or GitLab Geo. (Helix4Git is a great option for giving remote users local performance.)

5. Usability

There are also key differences in usability between ClearCase and Git.

ClearCase has more overhead and is more difficult to maintain. Git can be faster to set up, but it’s missing a lot of key features.

ClearCase has much more overhead than Git. It requires expensive administration. There are specific (and somewhat ridiculous) hardware requirements. And it’s brutal to set up in interop environments (including a restrictive server topology). Git is simpler to setup and maintain.

ClearCase is also harder to use and can be slow. Developers see Git as faster than ClearCase. However, simplicity comes with limits. Git doesn’t natively offer everything that ClearCase can do. To switch to Git, you’d be giving up a lot.

Which Is Easier to Use?

Overall, Git is easier to use and maintain. But that comes at a price…

6. Security

There is a vast difference in security between ClearCase and Git.

ClearCase has granular permissions and can support compliance needs. Git natively lacks security features and requires additional tools.

ClearCase’s permission structure ensures that no one accesses the repositories without appropriate credentials. Permissions are defined at the VOB level. Any changes a user makes are transcribed and maintained for traceability. Plus, admins can use scripts to enforce policies on a shared repository.

Git has no security features in its native form. Using tools such as Helix TeamHub, Bitbucket, GitHub, and GitLab add layers of security. This includes granular permissions, user management, and authentication measures.

Which Is More Secure?

ClearCase is natively more secure than Git. But you can improve Git security by adding tools.

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7. Cost and Availability

There is a major cost and availability difference between Git and ClearCase. 

Git is free open source software, but it probably will require proprietary add-ons that come at an additional cost. ClearCase is only proprietary — and it’s expensive.

Git is free (technically). But free isn’t always free. To use Git, you’ll either have to write tools on top or buy front-end tools (again Helix TeamHub, Bitbucket, GitHub, or GitLab).

ClearCase is expensive to license, use, and maintain. It also racks up costs in developer productivity, since it is difficult to use.

Which Is a Better Value?

It depends on how you look at it. If you have a small team of developers using Git efficiently, Git might deliver more value for its cost. But if you have a large, enterprise team, ClearCase will provide more value than Git.

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Should You Migrate From ClearCase to Git?

Many ClearCase teams are considering migrating to Git.

But should you?

ClearCase and Git aren’t your only options. There’s also Perforce Helix Core.

Why Helix Core Is Your Best Option

Helix Core is the best option to replace ClearCase.

If you have a huge monolithic repo in ClearCase, you can’t just migrate it to Git, as Git won’t be able to handle it. What you need to do is refactor it, modernize it, and make it easier to work on. And that’s why you should migrate to Helix Core.

Helix Core will solve the challenges that you’re having with ClearCase (and Git):

  • Architecture: Perforce Federated Architecture ensures high performance and accelerates CI/CD with lightning-fast commits and concurrent builds.
  • Repository Design: Helix Core can support your monorepo and scale to handle more files and users than ClearCase or Git — without slowing down. And if you have Git, you can bring that code into your pipeline with Helix4Git.
  • Branching and Merging: Perforce Streams offer a simple and better way to branch and merge. And you can get a merge preview and track merge history across branches.
  • Replication Model: Perforce Federated Architecture offers advanced replication, giving your remote teams faster access via edge and replica servers. And, unlike ClearCase, you can do backups without kicking out users.
  • Usability: Helix Core makes life easier for developers with features like Perforce Streams. It also makes life easier for admins with extensions and integrations that enhance automation and help you manage complex infrastructures.
  • Security: Helix Core offers file-level access control with greater authentication measures (including SSO and MFA). You can also maintain a full change history.
  • Cost and Availability: Helix Core has a per-user licensing model (starting with up to 5 users for free). And you can improve developer productivity, providing a better total cost of ownership.

Migrating from ClearCase doesn’t need to be costly. You can leverage the expertise of Perforce to move your monorepo to Helix Core, modernize it, and decide what that new architecture is going to look like.

Plus, with Helix Core, you don’t have to choose between the benefits of ClearCase and the benefits of Git. You get both. Helix Core scales and performs better than ClearCase. And Helix4Git is an add-on option that allows you to manage Git repos in a high-performance Helix Core server.

Get the best of both worlds. Switch from ClearCase to Helix Core.

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