From: Michael Vrable Date: Sat, 16 Dec 2006 07:32:15 +0000 (-0800) Subject: Begin work to document a proposed file format for backups. X-Git-Url: http://git.vrable.net/?a=commitdiff_plain;h=c93e446e6d0863dc8105884f38f7e33025dd7406;p=cumulus.git Begin work to document a proposed file format for backups. --- diff --git a/format.txt b/format.txt new file mode 100644 index 0000000..f7ce166 --- /dev/null +++ b/format.txt @@ -0,0 +1,27 @@ + Backup Format Description + for an LFS-Inspired Backup Solution + +NOTE: This is simply a proposal at this point in time, and not yet +implemented. Details are subject to change. + +======================================================================== + +Goals: To provide a stable and extensible data storage format for +efficient remote filesystem backups. Among the features desired in the +format are: + - Support for grouping unchanging file contents together, and reusing + it for future backups. + - Nonetheless allow old backups to be deleted (at least those parts + that are not also used by newer backups). + - Support some form of rdiff-style incremental differences within a + file. +The current plan is to implement compression and encryption separately: +not as part of the base format, but simply by passing the backup data +through filters such as bzip2 or gpg. + +Data is organized into a collection of _objects_, which are grouped +together for storage purposes into _segments_. Objects may refer to +other objects; a snapshot consists of a tree object which in turn refers +to other objects containing file data. A new snapshot may be created +which refers to some of the old objects with file data, if those files +have not changed.