Subversion MultiSite vs ClearCase MultiSite

Subversion's rapid adoption in the marketplace, low cost (it's free), relative ease of use, and minimal administrative overhead are leading many IT organizations to make the move away from ClearCase MultiSite. WANdisco builds on these advantages to transform Subversion into a true enterprise class multi-site solution that even the largest globally distributed IT organizations can rely upon.

With Subversion MultiSite, developers at every site experience LAN-speed performance for both reads and writes, and distributed Subversion repositories stay in sync in real-time. All developers, regardless of location, always work from the exact same code base. This completely changes the game by eliminating the need for the extensive branching and merging that is often the source of extra complexity, administrative overhead and delay with ClearCase MultiSite, as well as the other multi-site solutions available for Subversion. With WANdisco, problems are found and fixed as they occur. Less time is spent on QA and rework. Developers can collaborate in real-time, instead of working in silos. Development cycle times and costs go down dramatically.

Architecture	Peer-to-Peer, with no single point of failure. Subversion repositories at every site are writeable as well as readable for the entire code base. No site specific branches are required.	Master-slave. Master repository can become a single point of failure. Multi-master approach allows local writes for specific branches, but extra administration is required to support this.
Multi-Site Replication Approach	WANdisco uses an active-active model in which all Subversion repositories are writeable as well as readable. Replication happens automatically with each write operation and transactional consistency is guaranteed across all distributed Subversion repositories.	Master-slave model in which replication is triggered by pre-defined scripts, or on demand by administrators. Administrators at sending and receiving sites must verify that replication has completed successfully, and restart replication process if it fails. Scripts and third party tools can automate some of this.
Performance	LAN-speed performance at all sites for both read and write operations. Architected to optimize performance and minimize bandwidth usage over the WAN.	High overhead NFS-based WAN-speed performance. Chatty protocol results in slow performance and high bandwidth usage over the WAN.
Backup and Recovery	Built-in self-healing capabilities automate disaster recovery over a LAN or WAN after network or server outages, without administrator involvement. Continuous real-time backup, with zero downtime for full 24 by 7 operation. No third-party backup and recovery solutions are required.	Hot backups are not supported. This means that full 24 by 7 operation is not possible. Backup and recovery processes require third party solutions, and significant administrator involvement.
Versioning	Automatic with Subversion on each checkin. This makes it easy for previous versions to be recreated, checked out or viewed. Subversion uses a global revision approach that can eliminate the overhead of identifying individual file versions that go together to create a build.	Using Base ClearCase, labels must be manually created to identify file versions that go together to define change sets and create a build.
Administrative Overhead	Minimal, due to WANdisco's active-active replication, and automated backup and recovery capabilities. All sites can be administered from a single location with WANdisco. Subversion branches are easy to create, and with WANdisco, there is no need to set up separate branches for each site to avoid conflicts. However, merge tracking facilities are limited in the current release of Subversion. This will be addressed in the upcoming 1.5 release of Subversion.	Requires administrator expertise at each development site, due to replication approach and lack of automated backup and recovery facilities. Significant overhead also results from requirement to maintain separate branches for each site to avoid conflicts, and perform merge operations. UCM helps to simplify branch management and merge operations with graphical merge tracking capabilities.