1 Backup Format Description
2 for an LFS-Inspired Backup Solution
4 NOTE: This is simply a proposal at this point in time, and not yet
5 implemented. Details are subject to change.
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9 Goals: To provide a stable and extensible data storage format for
10 efficient remote filesystem backups. Among the features desired in the
12 - Support for grouping unchanging file contents together, and reusing
13 it for future backups.
14 - Nonetheless allow old backups to be deleted (at least those parts
15 that are not also used by newer backups).
16 - Support some form of rdiff-style incremental differences within a
18 The current plan is to implement compression and encryption separately:
19 not as part of the base format, but simply by passing the backup data
20 through filters such as bzip2 or gpg.
22 Data is organized into a collection of _objects_, which are grouped
23 together for storage purposes into _segments_. Objects may refer to
24 other objects; a snapshot consists of a tree object which in turn refers
25 to other objects containing file data. A new snapshot may be created
26 which refers to some of the old objects with file data, if those files