BorgBackup

BorgBackup (Borg) is an open-source, deduplicating backup program that provides efficient, encrypted, and compressed backups. It is widely used by hosting providers and system administrators for server backup due to its exceptional deduplication performance and space efficiency.

Borg's content-defined chunking deduplication means that identical data blocks across different backups (and even across different files) are stored only once. For hosting backups where most data does not change between daily runs, this results in dramatic space savings. A hosting server with 500GB of customer data might only use 550GB of backup storage for 30 daily backups, because only the changed blocks are stored.

Encryption is built-in and enabled by default. Borg uses AES-256-CTR for encryption and HMAC-SHA256 for authentication. All encryption happens client-side before data leaves the source server, so backup repositories on remote storage are always encrypted. This makes it safe to store backups on any storage service without worrying about data exposure.

Borg supports local and remote backup destinations. Remote repositories are accessed over SSH, requiring no special server software beyond SSH and Borg itself on the destination. This simplicity makes it easy to set up dedicated backup servers or use any SSH-accessible storage.

For hosting providers, Borg is typically used as the backend for nightly server backups. A cron job runs borg create to snapshot the entire server or specific directories, borg prune removes old backups according to retention policies, and borg compact reclaims freed space. The append-only mode feature prevents compromised servers from deleting their own backups, providing protection against ransomware.

Borg pairs well with BorgBase and Rsync.net for managed off-site backup storage. Some providers run their own Borg backup servers using cheap storage VPS instances, keeping backup costs low while maintaining geographic separation from production infrastructure.