bsync

Incremental, multi-version remote backup tool for block devices.

The on-disk backup format is a SQLite database and I've been dogfooding this on my homelab servers for a while, so I consider this quite stable.

Install

bsync implements pull-style synchronization and should be installed on the backup destination (pull-side) host. Get the latest binary from Releases.

The release workflow builds bsync for:

• Linux (x86_64, binary and .deb)
• macOS (x86_64, binary)
• FreeBSD (x86_64, binary)

Usage

bsync works over SSH and pulls changes to a block device from the remote host (backup source). Linux (x86_64, AArch64) is currently the only supported OS on the backup source.

Pull changes (see "Example config" below for an example of config.yaml):

$ bsync pull -c ./config.yaml

List local versions:

$ bsync list --db ./backup.db
 LSN   CREATED 
 21800  2021-10-19 08:21:51
 22267  2021-10-19 08:46:24
 30245  2021-10-20 00:22:38
 35319  2021-10-20 08:22:15

Build an image of the block device at a given point in time:

# Find `lsn` from `bsync list` output
$ bsync replay --db ./backup.db --lsn 30245 --output ./replay.img

Start an NBD server to serve a read-only version of the block device at a given point in time:

$ bsync serve --db ./backup.db --lsn 30245 --listen 127.0.0.1:2939
# Or, to listen on a unix socket
$ bsync serve --db ./backup.db --lsn 30245 --listen unix:/tmp/bsync.sock

Squash the backup to remove historic versions and free up space:

# Remove versions between LSN 21800 and 30245 (boundaries excluded) so that the remaining versions are
# 21800, 30245, 35319
$ bsync squash --db ./backup.db --start-lsn 21800 --end-lsn 30245 

Example config

The schema of the config file is defined as BackupConfig in src/config.rs and can be used as a reference.

Note that bsync doesn't automatically snapshot your volumes yet so please add your own snapshot logic (LVM, zvol, etc.) in remote.scripts.pre_pull to ensure data consistency. An example for backing up LVM thin volumes (taken from my homelab servers):

remote:
  server: 192.168.1.1
  user: root
  image: /dev/mapper/VG_data01-data--auto--snapshot--do--not--touch
  scripts:
    pre_pull: |
      set -e
      lvremove -y VG_data01/data-auto-snapshot-do-not-touch || true
      lvcreate -s VG_data01/data -n data-auto-snapshot-do-not-touch
      lvchange -ay -Ky VG_data01/data-auto-snapshot-do-not-touch
    post_pull: |
      lvremove -y VG_data01/data-auto-snapshot-do-not-touch
local:
  db: /backup/store.db
  pull_lock: /backup/store.lock