Efficient Incremental Backups for Subversion

Subversion 1.8 introduces an improved method for efficient incremental backups for Subversion. In a nutshell, the hotcopy command can run incrementally for faster backups.

To take a step back, Subversion repositories hold the intellectual property equivalent of your crown jewels, and guarding that data requires a layered strategy.

  • The first step is usually a local mirror that has a full copy of the repository data and can be used as a warm or hot spare. Of course, if you’re using WANdisco SVN MultiSite, every replicated peer has a complete set of data and failover is automated.

  • The second step is a remote mirror that has a full copy of the repository data and can be used for failover in a disaster recovery scenario. Again, SVN MultiSite provides this capability (and more) along with automated failover.

  • Finally, you need to have full offline backups of your repository data. Offline backups often progress through a storage cycle, with the most recent backups kept on faster, short-term storage and the oldest moving to cheaper offline storage. The backups generated by svnadmin hotcopy (possibly from a spare server) fall into this category.

Prior to Subversion 1.8, hotcopy created a full backup of the entire repository. The operation was often slow on large repositories, requiring careful scheduling or alternative strategies. Since hotcopy is only bound by disk I/O speed, it is faster than either native Subversion replication (svnsync) or creating incremental dump files, making it a great choice for a more efficient backup strategy. And of course hotcopy retains all of its usual advantages: it makes a full backup of a running repository in the right sequence to ensure data integrity.

Though hotcopy is only part of a layered backup strategy, it is a powerful tool for Subversion administrators not enjoyed by administrators of many commercial SCM systems. hotcopy is simple, reliable, and now pretty efficient. There are no concerns over backing up several parts of a complex system in the right order.

To use the incremental mode, simply use the new –incremental option. If you want to give it a try, download the latest certified SVN binaries for Subversion 1.8.

Subversion is a registered trademark of the Apache Foundation.


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