Module arq::packset

Packs

Each folder configured for backup maintains 2 "packsets", one for trees and commits, and one for all other small files. The packsets are named:

<folder_uuid>-trees
<folder_uuid>-blobs

Small files are separated into 2 packsets because the trees and commits are cached locally (so that Arq gives reasonable performance for browsing backups); all other small blobs don't need to be cached.

A packset is a set of "packs". When Arq is backing up a folder, it combines small files into a single larger packfile; when the packfile reaches 10MB, it is stored at the destination. Also, when Arq finishes backing up a folder it stores its unsaved packfiles no matter their sizes.

When storing a pack, Arq stores the packfile as:

/<computer_uuid>/packsets/<folder_uuid>-(blobs|trees)/<sha1>.pack

It also stores an index of the SHA1s contained in the pack as:

/<computer_uuid>/packsets/<folder_uuid>-(blobs|trees)/<sha1>.index

Structs

Pack	Pack File Format
PackIndex	Pack Index Format
PackIndexObject	PackIndexObject
PackObject	PackObject