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Please note that this is the README for borg2 / master branch.

For the stable version's docs, please see there:

https://borgbackup.readthedocs.io/en/stable/

Borg2 is currently in beta testing and might get major and/orbreaking changes between beta releases (and there is no beta tonext-beta upgrade code, so you will have to delete and re-create repos).

Thus,DO NOT USE BORG2 FOR YOUR PRODUCTION BACKUPS! Please help withtesting it, but set it upadditionally to your production backups.

TODO: the screencasts need a remake using borg2, see there:

#6303

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 back up data.The data deduplication technique used makes Borg suitable for daily backupssince only changes are stored.The authenticated encryption technique makes it suitable for backups to targets notfully trusted.

See theinstallation manual or, if you have alreadydownloaded Borg,docs/installation.rst to get started with Borg.There is also anoffline documentation available, in multiple formats.

Space efficient storage

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

A chunk is considered duplicate if its id_hash value is identical.A cryptographically strong hash or MAC function is used as id_hash, e.g.(hmac-)sha256.

To deduplicate, all the chunks in the same repository are considered, nomatter 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 aroundwithout killing the deduplication, even between machines sharing a repo.
• complete files or time stamps staying the same: If a big file changes alittle, only a few new chunks need to be stored - this is great for VMs orraw disks.
• The absolute position of a data chunk inside a file: Stuff may get shiftedand will still be found by the deduplication algorithm.

Speed

• performance-critical code (chunking, compression, encryption) isimplemented in C/Cython
• local caching
• quick detection of unmodified files

Data encryption

All data can be protected client-side using 256-bit authenticated encryption(AES-OCB or chacha20-poly1305), ensuring data confidentiality, integrity andauthenticity.

Obfuscation

Optionally, borg can actively obfuscate e.g. the size of files / chunks tomake fingerprinting attacks more difficult.

Compression

All data can be optionally compressed:

• lz4 (super fast, low compression)
• zstd (wide range from high speed and low compression to high compressionand lower speed)
• zlib (medium speed and compression)
• lzma (low speed, high compression)

Off-site backups

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

Backups mountable as filesystems

Backup archives are mountable as userspace filesystems for easy interactivebackup 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
• macOS
• FreeBSD
• OpenBSD and NetBSD (no xattrs/ACLs support or binaries yet)
• Cygwin (experimental, no binaries yet)
• Linux Subsystem of Windows 10 (experimental)

Free and Open Source Software

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

For ease of use, set the BORG_REPO environment variable:

$ export BORG_REPO=/path/to/repo

Create a new backup repository (seeborg repo-create --help for encryption options):

$ borg repo-create -e repokey-aes-ocb

Create a new backup archive:

$ borg create Monday1 ~/Documents

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

$ borg create -v --stats Monday2 ~/DocumentsRepository: /path/to/repoArchive name: Monday2Archive fingerprint: 7714aef97c1a24539cc3dc73f79b060f14af04e2541da33d54c7ee8e81a00089Time (start): Mon, 2022-10-03 19:57:35 +0200Time (end):   Mon, 2022-10-03 19:57:35 +0200Duration: 0.01 secondsNumber of files: 24Original size: 29.73 MBDeduplicated size: 520 B

Your help is always welcome!

Spread the word, give feedback, help with documentation, testing or development.

You can also give monetary support to the project, see there for details:

https://www.borgbackup.org/support/fund.html

• Main Web Site
• Releases,PyPI packages andChangeLog
• Offline Documentation
• GitHub andIssue Tracker.
• Web-Chat (IRC) andMailing List
• License
• Security contact

EXPECT THAT WE WILL BREAK COMPATIBILITY REPEATEDLY WHEN MAJOR RELEASE NUMBERCHANGES (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.

Security issues should be reported to theSecurity contact (orseedocs/support.rst in the source distribution).