Terminology
These terms are commonly used in this documentation and within the app.
BorgBackup
BorgBackup is the underlying program that is used to create backups. Pika Backup repositories can also be accessed with the BorgBackup commandline utility. See BorgBackup documentation for more information about how to use the borg command line utility.
Repository
Backup repositories are directories on a disk or on a remote location that contain backup data. They store one or more archives.
Archive
Every backup will create one archive. They store a singular snapshot of the files at the time the backup was created. To restore data from a particular archive, see Recovery.
Deduplication
Pika Backup stores backup archives in a way that only new and changed data from the last backup use up more disk space. The term deduplication is used to refer to this functionality.
The amount of new space used for the last backup can be seen in the Backup Info window that can be accessed via the Backup tab.
Compression
Backup archives created with Pika Backup are compressed with the zstd algorithm on level 3. This was chosen as a compromise between performance and resulting backup size.
Encryption
Backup repositories created with Pika Backup can be encrypted. This will make it impossible for anyone to read the contents of the backup without knowing or guessing the encryption password.
While it is important to choose a strong encryption password for sensitive data, losing the password also means losing access to all data. It is equally important to choose a password that is not easily forgotten or stored in a safe place.
The encryption algorithm used for new repositories is AES-CTR-256. The authentication algorithm is either HMAC-SHA256 or BLAKE2b-256 depending on whether SHA256 is hardware-accelerated on the system.
The encryption password can be changed via Menu ▸ Backup Preferences ▸ Change Encryption Password.