voltara / borg

Deduplicating backup program with compression and authenticated encryption.

What is BorgBackup?

BorgBackup (short: Borg) is a deduplicating backup program. Optionally, it supports compression and authenticated encryption.

The main goal of Borg is to provide an efficient and secure way to backup data. The data deduplication technique used makes Borg suitable for daily backups since only changes are stored. The authenticated encryption technique makes it suitable for backups to not fully trusted targets.

See the installation manual or, if you have already downloaded Borg, docs/installation.rst to get started with Borg.

Main features

Space efficient storage

Deduplication based on content-defined chunking is used to reduce the number of bytes stored: each file is split into a number of variable length chunks and only chunks that have never been seen before are added to the repository.

To deduplicate, all the chunks in the same repository are considered, no matter whether they come from different machines, from previous backups, from the same backup or even from the same single file.

Compared to other deduplication approaches, this method does NOT depend on:

• file/directory names staying the same: So you can move your stuff around without killing the deduplication, even between machines sharing a repo.
• complete files or time stamps staying the same: If a big file changes a little, only a few new chunks need to be stored - this is great for VMs or raw disks.
• The absolute position of a data chunk inside a file: Stuff may get shifted and will still be found by the deduplication algorithm.

Speed

• performance critical code (chunking, compression, encryption) is implemented in C/Cython
• local caching of files/chunks index data
• quick detection of unmodified files

Data encryption

All data can be protected using 256-bit AES encryption, data integrity and authenticity is verified using HMAC-SHA256. Data is encrypted clientside.

Compression

All data can be compressed by lz4 (super fast, low compression), zlib (medium speed and compression) or lzma (low speed, high compression).

Off-site backups

Borg can store data on any remote host accessible over SSH. If Borg is installed on the remote host, big performance gains can be achieved compared to using a network filesystem (sshfs, nfs, ...).

Backups mountable as filesystems

Backup archives are mountable as userspace filesystems for easy interactive backup examination and restores (e.g. by using a regular file manager).

Easy installation on multiple platforms

We offer single-file binaries that do not require installing anything - you can just run them on these platforms:

• Linux
• Mac OS X
• FreeBSD
• OpenBSD and NetBSD (no xattrs/ACLs support or binaries yet)
• Cygwin (not supported, no binaries yet)

Free and Open Source Software

• security and functionality can be audited independently
• licensed under the BSD (3-clause) license

Easy to use

Initialize a new backup repository and create a backup archive:

$ borg init /path/to/repo
$ borg create /path/to/repo::Saturday1 ~/Documents

Now doing another backup, just to show off the great deduplication:

$ borg create -v --stats /path/to/repo::Saturday2 ~/Documents
-----------------------------------------------------------------------------
Archive name: Saturday2
Archive fingerprint: 622b7c53c...
Time (start): Sat, 2016-02-27 14:48:13
Time (end):   Sat, 2016-02-27 14:48:14
Duration: 0.88 seconds
Number of files: 163
-----------------------------------------------------------------------------
               Original size      Compressed size    Deduplicated size
This archive:        6.85 MB              6.85 MB             30.79 kB  <-- !
All archives:       13.69 MB             13.71 MB              6.88 MB

               Unique chunks         Total chunks
Chunk index:             167                  330
-----------------------------------------------------------------------------

For a graphical frontend refer to our complementary project BorgWeb.

Links

• Main Web Site
• Releases
• PyPI packages
• ChangeLog
• GitHub
• Issue Tracker
• Bounties & Fundraisers
• Mailing List
• License

Notes

Borg is a fork of Attic and maintained by "The Borg collective".

Differences between Attic and Borg

Here's a (incomplete) list of some major changes:

• more open, faster paced development (see issue #1)
• lots of attic issues fixed (see issue #5)
• less chunk management overhead (less memory and disk usage for chunks index)
• faster remote cache resync (useful when backing up multiple machines into same repo)
• compression: no, lz4, zlib or lzma compression, adjustable compression levels
• repokey replaces problematic passphrase mode (you can't change the passphrase nor the pbkdf2 iteration count in "passphrase" mode)
• simple sparse file support, great for virtual machine disk files
• can read special files (e.g. block devices) or from stdin, write to stdout
• mkdir-based locking is more compatible than attic's posix locking
• uses fadvise to not spoil / blow up the fs cache
• better error messages / exception handling
• better logging, screen output, progress indication
• tested on misc. Linux systems, 32 and 64bit, FreeBSD, OpenBSD, NetBSD, Mac OS X

Please read the ChangeLog (or docs/changes.rst in the source distribution) for more information.

BORG IS NOT COMPATIBLE WITH ORIGINAL ATTIC (but there is a one-way conversion).

EXPECT THAT WE WILL BREAK COMPATIBILITY REPEATEDLY WHEN MAJOR RELEASE NUMBER CHANGES (like when going from 0.x.y to 1.0.0 or from 1.x.y to 2.0.0).

NOT RELEASED DEVELOPMENT VERSIONS HAVE UNKNOWN COMPATIBILITY PROPERTIES.

THIS IS SOFTWARE IN DEVELOPMENT, DECIDE YOURSELF WHETHER IT FITS YOUR NEEDS.

Borg is distributed under a 3-clause BSD license, see License for the complete license.