Borg Backup

"The holy grail of backup software?"

Thomas Waldmann (Dec 2016)

Borg - a fork of Attic

• Attic: about 5y old, good design, proven code

• but:

  • development going slowly

  • some bugs and annoyances

  • not very open to new developers
     

• Borg Backup: fork of Attic, now ~1.5y old

• and:

  • a community project, bus_factor++

  • lots of fixes and good PRs merged

  • open and inviting to new contributors

  • faster paced, lots of activity

Feature Set (1)

• easy and fast
• content-defined chunking (*)
• chunk deduplication (*)
• lz4, zlib, lzma compression

• encryption with AES256

• authentication with HMAC-SHA2

• simple backend (k/v, fs, via ssh)

Feature Set (2)

• FOSS (BSD license)

• good docs

• good platform / arch support

• xattr / acl / bsdflags support

• mount a backup via FUSE

• Python 3.4+, a little Cython & C

• good test coverage, CI

Deduplication (1)

• No problem with:
  • VM images (sparse file support)
  • (physical) disks, LV snapshots
  • renamed huge directories
  • inner deduplication of data set
  • historical deduplication
  • dedups different machines

Deduplication (2)

• Content defined chunking:
  • "buzhash" rolling hash
  • cut data when hash has specific bit pattern,
    yields chunks with ~ 2^n bytes target size
  • n + other chunker params configurable now
  • seeded, to avoid fingerprinting chunk lengths
     
• Store chunks under id into store:
  • id = HASH(chunk), or
  • id = HMAC(id_key, chunk)

Now and Future

• 1.0 released   --   important: use 1.0.6+
   
• soon:  1.1  (new features, code cleanup)
   
• 1.2   Crypto Enhancements
  • AES-GCM (AES-OCB? chacha20-poly1305?)
  • Key Management
  • Ciphersuite Flexibility
     
• 1.2   Parallelization
  • "Serial Threaded Workers"   (avoids races)
  • or use py /cy async instead of threads?

Borg Backup - Links

github.com/borgbackup
 

#borgbackup  on  chat.freenode.net

Questions / Feedback?

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an introduction into the code.