Linux

• daily important stuff (job stuff, Documents folder, Renoise mods) is kept synced between laptop, desktop and home server via Syncthing. A vimwiki additionally also syncs with the phone. Sync happens only when on home network.

• the rest of the laptop and desktop I'll roll into a tar backup every now and then with a quick bash alias. The tar files also get synced onto home server's big file system (2 TB ssd) via Syncthing. Home server backs itself up on it's own once a week.

• clever thing is that the 2 TB ssd replaced an old 2 TB spinning disk. I kept the old disk and set up a systemd thing that keeps it spun down, but starts and mounts it once a week and rsyncs the changes to the ssd over, then unmounts it so that it sleeps again for a week. That old drive is likely to serve for years still with this frugal use.

Using timeshift. Very, very easy, works great.

Borg daily to the local drive then copied across to a USB drive, then weekly to cloud storage. Script is triggered by daily runs of topgrade before I do any updates

I created a script that I dropped into /etc/cron.hourly which does the following:

1. Use rsync to mirror my root partition to a btrfs partition on another hard drive (which only updates modified files).
2. Use btrfs subvolume snapshot to create a snapshot of that mirror (which only uses additional storage for modified files).
3. Moves "old" snapshots into a trash directory so I can delete them later if I want to save space.

It is as follows:

#!/usr/bin/env python
from datetime import datetime, timedelta
import os
import pathlib
import shutil
import subprocess
import sys

import portalocker

DATETIME_FORMAT = '%Y-%m-%d-%H%M'
BACKUP_DIRECTORY = pathlib.Path('/backups/internal')
MIRROR_DIRECTORY = BACKUP_DIRECTORY / 'mirror'
SNAPSHOT_DIRECTORY = BACKUP_DIRECTORY / 'snapshots'
TRASH_DIRECTORY = BACKUP_DIRECTORY / 'trash'

EXCLUDED = [
    '/backups',
    '/dev',
    '/media',
    '/lost+found',
    '/mnt',
    '/nix',
    '/proc',
    '/run',
    '/sys',
    '/tmp',
    '/var',

    '/home/*/.cache',
    '/home/*/.local/share/flatpak',
    '/home/*/.local/share/Trash',
    '/home/*/.steam',
    '/home/*/Downloads',
    '/home/*/Trash',
]

OPTIONS = [
    '-avAXH',
    '--delete',
    '--delete-excluded',
    '--numeric-ids',
    '--relative',
    '--progress',
]

def execute(command, *options):
    print('>', command, *options)
    subprocess.run((command,) + options).check_returncode()

execute(
    '/usr/bin/mount',
    '-o', 'rw,remount',
    BACKUP_DIRECTORY,
)

try:
    with portalocker.Lock(os.path.join(BACKUP_DIRECTORY,'lock')):
        execute(
            '/usr/bin/rsync',
            '/',
            MIRROR_DIRECTORY,
            *(
                OPTIONS
                +
                [f'--exclude={excluded_path}' for excluded_path in EXCLUDED]
            )
        )

        execute(
            '/usr/bin/btrfs',
            'subvolume',
            'snapshot',
            '-r',
            MIRROR_DIRECTORY,
            SNAPSHOT_DIRECTORY / datetime.now().strftime(DATETIME_FORMAT),
        )

        snapshot_datetimes = sorted(
            (
                datetime.strptime(filename, DATETIME_FORMAT)
                for filename in os.listdir(SNAPSHOT_DIRECTORY)
            ),
        )

        # Keep the last 24 hours of snapshot_datetimes
        one_day_ago = datetime.now() - timedelta(days=1)
        while snapshot_datetimes and snapshot_datetimes[-1] >= one_day_ago:
            snapshot_datetimes.pop()

        # Helper function for selecting all of the snapshot_datetimes for a given day/month
        def prune_all_with(get_metric):
            this = get_metric(snapshot_datetimes[-1])
            snapshot_datetimes.pop()
            while snapshot_datetimes and get_metric(snapshot_datetimes[-1]) == this:
                snapshot = SNAPSHOT_DIRECTORY / snapshot_datetimes[-1].strftime(DATETIME_FORMAT)
                snapshot_datetimes.pop()
                execute('/usr/bin/btrfs', 'property', 'set', '-ts', snapshot, 'ro', 'false')
                shutil.move(snapshot, TRASH_DIRECTORY)

        # Keep daily snapshot_datetimes for the last month
        last_daily_to_keep = datetime.now().date() - timedelta(days=30)
        while snapshot_datetimes and snapshot_datetimes[-1].date() >= last_daily_to_keep:
            prune_all_with(lambda x: x.date())

        # Keep weekly snapshot_datetimes for the last three month
        last_weekly_to_keep = datetime.now().date() - timedelta(days=90)
        while snapshot_datetimes and snapshot_datetimes[-1].date() >= last_weekly_to_keep:
            prune_all_with(lambda x: x.date().isocalendar().week)

        # Keep monthly snapshot_datetimes forever
        while snapshot_datetimes:
            prune_all_with(lambda x: x.date().month)
except portalocker.AlreadyLocked:
    sys.exit('Backup already in progress.')
finally:
    execute(
        '/usr/bin/mount',
        '-o', 'ro,remount',
        BACKUP_DIRECTORY,
    )

I use Pika Backup (GUI that uses Borg Backup on the backend) to back up my desktop to my home server daily, then overnight that server has a daily backup using Borg to a Hetzner Storage Box. It's easy to set it and forget it (other than maybe verifying the backups every once in a while), and having that off site back up gives me peace of mind.