Long-term archival backups for Linux — with integrity you can prove and repair
dar-backup is for Linux users who want serious, long-term backups — not just file copies.
It automates FULL / DIFF / INCR archive cycles built on two exceptional open-source tools:
- dar (Disk ARchiver) — a powerful, actively maintained
archiver by Denis Corbin that handles differential and incremental archives, built-in
verification, catalogue databases, and precise file selection.
daris the engine that makes long-term archival practical. It deserves to be far better known than it is. - par2cmdline — the Parchive suite's implementation of PAR2, a Reed-Solomon based redundancy format that can detect and repair corruption in any file, years after the fact, with no connection to the original source. A quiet but remarkable piece of technology.
dar-backup wires these two tools together into a fully automated backup system, with every
archive verified and restore-tested before the job completes.
Is this for you?
✅ You back up irreplaceable data — photos, documents, home-made video — and want to be certain you can restore any file to any point in time, years from now
✅ You run backups as a normal user — root is not required, and FUSE-mounted filesystems (Nextcloud, rclone, sshfs) work correctly
✅ You want bitrot repair to travel with your archives — onto USB disks, offsite copies, and cloud storage — without depending on the original system
✅ You want unattended, scheduled backups with Discord notifications on success or failure
✅ You want a transparent, no-lock-in tool built on proven Unix components
✗ You need a GUI, Windows support, or just a quick incremental sync — rsync or restic may suit you better
✗ You need multiple backups per day — dar-backup is designed around one backup run per day
per definition (one FULL, one DIFF, one INCR). If you need hourly or continuous backups,
look at restic or BorgBackup instead
# prep
sudo apt -y install dar par2 python3 python3-venv
INSTALL_DIR=/tmp/dar-backup; mkdir "$INSTALL_DIR" && cd "$INSTALL_DIR"
python3 -m venv venv # create a virtual environment
. venv/bin/activate # activate the virtual environment
# install and run dar-backup
pip install dar-backup
demo --install && manager --create-db
dar-backup --full-backupdar-backup runs FULL, DIFF, and INCR backup cycles across as many backup definitions as you
need (e.g. photos, documents, homevideos). After each archive it:
- Verifies the archive with
dar -t - Restore-tests a random sample of files and compares them byte-for-byte against the source
- Creates PAR2 redundancy files so the archive can be repaired if bitrot occurs later
- Notifies your Discord channel on completion or failure
Schedules are managed by systemd timers (generated for you). Catalogs of every archive are
maintained by dar_manager, enabling single-file Point-in-Time Recovery without a database
server.
Version 1.1.2 · reached 1.0.0 on October 9, 2025 · Changelog
Those are excellent tools. dar-backup fills a different niche:
| Concern | dar-backup |
|---|---|
| Run as non-root on FUSE mounts | ✅ designed for this |
| Bitrot repair without re-downloading | ✅ PAR2 travels with the archive |
| Restore a single file to a specific date | ✅ PITR via dar_manager catalogs |
| No dependency on original system to restore | ✅ one static dar binary is enough |
| Archive integrity testable anywhere | ✅ par2verify + dar -t work offline |
| Transparent, auditable backup content | ✅ dar archives are well-documented |
If your threat model is "I need to recover a file I deleted three months ago, on a machine I
no longer have, from a USB disk I kept offsite" — dar-backup is built for exactly that.
tar is the tool almost every Linux user reaches for first — and for good reason. It is simple, universal, and ships on every system. dar was written as a deliberate improvement on tar for long-term archival, and the differences matter:
| Capability | tar | dar-backup |
|---|---|---|
| FULL / DIFF / INCR backup cycles | ❌ workarounds only | ✅ native, first-class |
| Archive integrity test | ❌ no built-in verify | ✅ dar -t after every backup |
| Restore-test a random sample | ❌ manual | ✅ automatic after each run |
| Repair a corrupt archive | ❌ not possible | ✅ PAR2 files travel with the archive |
| Restore a single file to a specific date | ❌ no catalogue | ✅ PITR via dar_manager catalogs |
| Sliced archives (fits onto fixed-size media) | ❌ | ✅ configurable slice size |
| Extended attributes and ACLs | ✅ handled correctly by default | |
| No dependency on original system to restore | ✅ | ✅ one static dar binary is enough |
In short: tar is excellent for one-off archiving and moving files around.
dar-backup is for people who want to know their data is intact and recoverable — years from now,
on hardware they don't own yet.
- FULL / DIFF / INCR backup cycles — per backup definition, independently scheduled
- Automatic archive verification —
dar -tafter every backup run - Automatic restore test — random files extracted and compared to source after each backup; configurable excludes for cache dirs, temp files, locks
- PAR2 redundancy — configurable coverage per backup type (FULL/DIFF/INCR); optionally stored in a separate directory (different device or offsite mount)
- Point-in-Time Recovery —
dar_managercatalogs let you locate and restore any file to any date across your full archive history - Metrics and dashboard - optional detailed metrics and dashboard
- Runs as a normal user — no root needed; works correctly on FUSE-mounted filesystems
- systemd integration — timer units generated for you with sensible default schedules
- Discord notifications — webhook alerts on backup success or failure, from all CLI tools
- Shell autocompletion — bash and zsh, context-aware (archive names filtered by definition)
- Clean logging — three log files (main, command output, trace/debug), all rotating and
size-capped;
clean-logstrips verbosedaroutput when not needed - No lock-in — standard
dararchives, standard PAR2 files; restore with just thedarbinary, nodar-backupinstallation required on the restore machine - 750+ tests — unit and integration tests covering PAR2 bitrot repair, full/diff/incr restore chains, PITR verification, and edge cases; CI on every commit
✅ The author has used dar-backup ~5 years and has been saved by it multiple times.
dar-backupstands on the shoulders of two projects that do the real work. Sincere thanks to Denis Corbin fordar, and to the Parchive team forpar2. If you finddar-backupuseful, consider giving those projects a star too.
Every backup run writes structured metrics to a SQLite database. The built-in
dar-backup-dashboard command fires up datasette and
opens the dashboard in your browser:
→ Dashboard & metrics documentation
| Document | Description |
|---|---|
| Quick Guide | Get started in minutes using the demo app |
| Getting Started | Manual setup for a real installation |
| Configuration Reference | Config file, .darrc, backup definitions, config history |
| Restoring | Point-in-Time Recovery (PITR), restore examples |
| PAR2 Redundancy | Verify, repair, and create PAR2 files |
| systemd Setup | Generate and install systemd timers/services |
| Shell Autocompletion | Bash and zsh tab-completion setup |
| Dashboard & Metrics | Metrics database, Datasette, dashboard |
| dar Tips | File selection, merging archives, logging tips |
| CLI Reference | All command options, exit codes, env vars |
| Troubleshooting | Error codes, FUSE issues, special characters |
| Development | Dev setup, testing, PyPI, building dar |
| Changelog | High-level release history |
| Detailed Changelog | Per-release details |
I needed the following:
-
Backup my workstation to a remote server
-
Backup primarily photos, home made video and different types of documents
-
I have cloud storage mounted on a directory within my home dir. The filesystem is FUSE based, which gives it a few special features
- Backup my cloud storage (cloud is convenient, but I want control over my backups)
- A non-privileged user can perform a mount
- A privileged user cannot look into the filesystem --> a backup script running as root is not suitable
-
Have a simple way of restoring, possibly years into the future. 'dar' fits that scenario with a single statically linked binary (kept with the archives). There is no need install/configure anything - restoring is simple and works well.
-
During backup archives must be tested and a restore test (however small) performed
-
Archives stored on a server with a reliable file system (easy to mount a directory over sshfs)
-
Easy to verify archive's integrity, after being moved around.
I do not need the encryption features of dar, as all storage is already encrypted.
-
Primary backup to server with an ext4 file system on mdadm RAID1
-
Secondary copies to multiple USB disks / cloud
-
Archive integrity verification anywhere using Par2 and
dar -t. -
Archive repair anywhere if needed. By default
dar-backupcreates par2 redundancy files with 5% coverage. Enough to fix localized bitrot. -
No dependency on original system
PAR2 parity is:
Self-contained (travels with the data)
Format-agnostic (works on any filesystem)
Location-agnostic (local disk, USB, cloud object storage)
Tool-stable (PAR2 spec has not changed in years)
That means:
Integrity protection moves with the archive.
My design choices are boring, proven and pragmatic:
- mdadm handles disks
- PAR2 handles data integrity
- You control when and how verification happens
- Errors have a fair chance of being diagnosed and fixed, due to well known tooling.
- No hidden magic, no lock-in
Step-by-step walkthrough using the built-in demo application — install, backup, list, restore.
dar-backup is built in a way that emphasizes getting backups. It loops over the backup definitions, and in the event of a failure while backing up a backup definition, dar-backup shall log an error and start working on the next backup definition.
There are 3 levels of backups, FULL, DIFF and INCR.
-
The author does a FULL yearly backup once a year. This includes all files in all directories as defined in the backup definition(s) (assuming
-dwas not given). -
The author makes a DIFF once a month. The DIFF backs up new and changed files compared to the FULL backup.
- No DIFF backups are taken until a FULL backup has been taken for a particular backup definition.
-
The author takes an INCR backup every 3 days. An INCR backup includes new and changed files compared to the DIFF backup.
-
So, a set of INCR's will contain duplicates (this might change as I become more used to use the catalog databases)
-
No INCR backups are taken until a DIFF backup has been taken for a particular backup definition.
-
After each backup of a backup definition, dar-backup tests the archive and then performs a few restore operations of random files from the archive (see config file). The restored files are compared to the originals to check if the restore went well.
dar-backup skips doing a backup of a backup definition if an archive is already in place. So, if you for some reason need to take a new backup on the same date, the first archive must be deleted (I recommend using cleanup).
The cleanup application deletes DIFF and INCR if the archives are older than the thresholds set up in the configuration file.
cleanup will only remove FULL archives if the option --cleanup-specific-archives is used. It requires the user to confirm deletion of FULL archives.
Use --dry-run to preview which archives, PAR2 files, and catalogs would be removed without deleting anything.
Examples:
cleanup --dry-run -d media-files --log-stdout
cleanup --dry-run --cleanup-specific-archives -d media-files media-files_INCR_2025-12-22darhas the concept of catalogs which can be exported and optionally be added to a catalog database. That database makes it much easier to restore the correct version of a backed up file if for example a target date has been set.
dar-backup adds archive catalogs to their databases (using the manager script). Should the operation fail, dar-backup logs an error and continue with testing and restore validation tests.
Manual setup for a real installation — configuration, catalog databases, first backup.
1.0.0 milestone reached
October 9, 2025, version 1.0.0 was released after extensive testing. The current release is 1.1.2.
To increase the security and authenticity of dar-backup packages, all releases from v2-beta-0.6.18 onwards will be digitally signed using the GPG key below.
🎯 GPG Signing Key Details
Name: Per Jensen (author of dar-backup)
Email: dar-backup@pm.me
Primary key: 4592 D739 6DBA EFFD 0845 02B8 5CCE C7E1 6814 A36E
Signing key: B54F 5682 F28D BA36 22D7 8E04 58DB FADB BBAC 1BB1
Created: 2025-03-29
Expires: 2030-03-28
Key type: ed25519 (primary, SC)
Subkeys: ed25519 (S), ed25519 (A), cv25519 (E)
🎯 Where to Find Release Signatures
PyPI does Not host .asc Signature Files
Although the dar-backup packages on PyPI are GPG-signed, PyPI itself does not support uploading .asc detached signature files alongside .whl and .tar.gz artifacts.
Therefore, you will not find .asc files on PyPI.
Where to Get .asc Signature Files
You can always download the signed release artifacts and their .asc files from the official GitHub Releases page:
📁 GitHub Releases for dar-backup
Each release includes:
-
dar_backup-x.y.z.tar.gz -
dar_backup-x.y.z.tar.gz.asc -
dar_backup-x.y.z-py3-none-any.whl -
dar_backup-x.y.z-py3-none-any.whl.asc
🎯 How to Verify a Release from GitHub
-
Import the GPG public key:
curl https://keys.openpgp.org/vks/v1/by-fingerprint/4592D7396DBAEFFD084502B85CCEC7E16814A36E | gpg --import -
Download the wheel or tarball and its .asc signature from the GitHub.
-
Run GPG to verify it:
gpg --verify dar_backup-x.y.z.tar.gz.asc dar_backup-x.y.z.tar.gz # or gpg --verify dar_backup-x.y.z-py3-none-any.whl.asc dar_backup-x.y.z-py3-none-any.whl -
If the signature is valid, you'll see:
gpg: Good signature from "Per Jensen (author of dar-backup) <dar-backup@pm.me>"
🛡️ Reminder: Verify the signing subkey
Only this subkey is used to sign PyPI packages:
B54F 5682 F28D BA36 22D7 8E04 58DB FADB BBAC 1BB1
You can view it with:
gpg --list-keys --with-subkey-fingerprints dar-backup@pm.meThese scripts are licensed under the GPLv3 license. Read more here: GNU GPL3.0, or have a look at the "LICENSE" file in this repository.
- A linux system
- dar
- parchive (par2)
- python3
- python3-venv
On Ubuntu, install the requirements this way:
sudo apt install dar par2 python3 python3-venv'dar-backup' package lives here: Github - dar-backup
Please review the Code of Conduct to help keep this project welcoming and focused.