btrfs-sync

Note: This fork simply adds in-transfer zstd compression support and snapshot locking capability (see Features)

Smart and easy sync of BTRFS snapshots, locally or through SSH.

See example gif.

Can be used in conjunction with btrfs-snp

# btrfs-sync --verbose --delete /home/user/.snapshots user@server:/media/USBdrive/home-snapshots
* Skip existing '/home/user/.snapshots/monthly_2018-01-09_200102'
* Skip existing '/home/user/.snapshots/monthly_2018-02-08_200102'
* Skip existing '/home/user/.snapshots/weekly_2018-02-09_140102'
* Skip existing '/home/user/.snapshots/weekly_2018-02-16_150102'
* Skip existing '/home/user/.snapshots/weekly_2018-02-23_150102'
* Skip existing '/home/user/.snapshots/weekly_2018-03-02_180102'
* Skip existing '/home/user/.snapshots/daily_2018-03-03_000101'
* Skip existing '/home/user/.snapshots/daily_2018-03-04_080101'
* Skip existing '/home/user/.snapshots/daily_2018-03-05_100102'
* Skip existing '/home/user/.snapshots/daily_2018-03-06_100102'
* Skip existing '/home/user/.snapshots/daily_2018-03-07_110102'
* Synchronizing '/home/user/.snapshots/hourly_2018-03-08_090101' using seed '.snapshots/hourly_2018-03-07_090101'...
time elapsed [0:00:24] | rate [11.1MiB/s] | total size [ 132MiB]
* Synchronizing '/home/user/.snapshots/hourly_2018-03-08_100101' using seed '.snapshots/hourly_2018-03-09_090101'...
time elapsed [0:01:05] | rate [11.1MiB/s] | total size [ 275MiB]
* Deleting non existent snapshots...
Delete subvolume (no-commit): '/media/USBdrive/home-snapshots/hourly_2018-03-08_090101'
Delete subvolume (no-commit): '/media/USBdrive/home-snapshots/hourly_2018-03-08_100101'

Features

Simple syntax
Optional progress indication (using pv)
Support for zstd, xz or pbzip2 compression in order to save bandwidth.
Snapshot locking while sync (btrfs-send) is in progress to prevent snapshot deletion, namely by btrfs subvolume delete ... invoked e.g as part of btrfs-snp
Retention policy
Automatic incremental synchronization
Cron friendly

Usage

The syntax is similar to that of scp

Usage:
  btrfs-sync [options] <src> [<src>...] [[user@]host:]<dir>

  -k|--keep NUM     keep only last <NUM> sync'ed snapshots
  -d|--delete       delete snapshots in <dst> that don't exist in <src>
  -z|--xz           use xz     compression. Saves bandwidth, but uses one CPU
  -Z|--pbzip2       use pbzip2 compression. Saves bandwidth, but uses all CPUs
  -s|--zstd         use zstd compression.
  -q|--quiet        don't display progress
  -v|--verbose      display more information
  -h|--help         show usage

<src> can either be a single snapshot, or a folder containing snapshots
<user> requires privileged permissions at <host> for the 'btrfs' command

Examples

Manual

Synchronize snapshots of home to a USB drive

# btrfs-sync /home/user/.snapshots /media/USBdrive/home-snapshots

Synchronize snapshots of home to a USB drive in another machine

# btrfs-sync /home/user/.snapshots user@server:/media/USBdrive/home-snapshots

Synchronize one snapshot of home to a USB drive in another machine

# btrfs-sync /home/user/.snapshots/monthly_2018-02-08_200102 user@server:/media/USBdrive/home-snapshots

Synchronize only monthly snapshots of home to a USB drive in another machine

# btrfs-sync /home/user/.snapshots/monthly_* user@server:/media/USBdrive/home-snapshots

Cron

Daily synchronization over the internet, keep only last 50

cat > /etc/cron.daily/btrfs-sync <<EOF
#!/bin/bash
/usr/local/sbin/btrfs-sync --quiet --keep 50 --xz /home user@host:/path/to/snaps
EOF
chmod +x /etc/cron.daily/btrfs-sync

Daily synchronization in LAN, mirror snapshot directory

cat > /etc/cron.daily/btrfs-sync <<EOF
#!/bin/bash
/usr/local/sbin/btrfs-sync --quiet --delete /home user@host:/path/to/snaps
EOF
chmod +x /etc/cron.daily/btrfs-sync

Credits

Original work by nachoparker of ownyourbits.com

zstd compression support and snapshot locking capability added by wanderer of dotya.ml

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