Backup

Rsync-based multi-platform backup scripts with rotation support.

Overview

Two backup strategies are provided:

• Generic — SSH-based remote backup with automatic hourly/daily/weekly rotation
• ZFS — Local or mounted filesystem sync (designed for use with ZFS snapshots)

Generic (SSH Remote Backup)

Pulls data from a remote host over SSH using rsync with hard-link-based deduplication. Backups are automatically rotated into hourly, daily, and weekly tiers.

Usage

Generic/SSHBackup.sh <source host> <source path> <target path>

• source host — hostname or IP of the remote machine (must have SSH key auth configured)
• source path — path on the remote machine to back up
• target path — local directory to store backups (must end with /)

How It Works

1. Acquires a PID-based lockfile (stale locks from crashed processes are detected and removed)
2. Verifies SSH connectivity to the remote host
3. Runs rsync with --link-dest to deduplicate unchanged files against the previous backup
4. Moves the completed backup into hourly/ and atomically updates the current symlink
5. Promotes the oldest hourly backup to daily/ if no recent daily exists
6. Promotes the oldest daily backup to weekly/ if no recent weekly exists
7. Cleans up old backups (hourly: >1 day, daily: >7 days, incomplete: >2 hours)

All output is logged to <target>/backup.log.

Retention Policy

Tier	Kept For
Hourly	1 day
Daily	7 days
Weekly	No automatic deletion

Directory Structure

<target>/
  current        -> symlink to latest backup
  lockfile       -> PID-based lock to prevent concurrent runs
  backup.log     -> append-only log of all backup runs
  hourly/
    2024-01-15T10_00_00/
    2024-01-15T11_00_00/
  daily/
    2024-01-14T10_00_00/
  weekly/
    2024-01-07T10_00_00/

Wrapper

Edit Generic/Wrapper.sh to set your source host, source path, and target path, then schedule it with cron:

# Run every hour
0 * * * * /path/to/Generic/Wrapper.sh

ZFS (Local Sync Backup)

Syncs a local or mounted filesystem to a target directory using rsync. Designed for use with ZFS, where snapshots provide the versioning layer.

Usage

ZFS/SyncBackup.sh <source path> <target path>

• source path — local directory to back up (must contain a lastbackup.txt file)
• target path — local directory to sync to

How It Works

1. Checks for lastbackup.txt in the source to verify the filesystem is mounted and valid
2. Timestamps the source with the current date
3. Runs rsync with --delete-after and --delete-excluded for a clean mirror

All output is logged to <target>/backup.log.

Wrapper

Edit ZFS/Wrapper.sh to set your source and target paths, then schedule it with cron:

# Run every hour
0 * * * * /path/to/ZFS/Wrapper.sh

Excluded Directories

Exclusions are managed via excludes.txt files alongside each script — one pattern per line. Edit these to add or remove exclusions without modifying the scripts.

Default exclusions:

• DoNotBackup — user-designated exclusion marker
• BBC iPlayer, Final Cut Events, Final Cut Projects, iMovie Events.localized — large media caches
• $RECYCLE.BIN, System Volume Information — Windows system directories (ZFS only)

Configuration

Each script has configurable variables at the top:

Variable	Default	Description
rsync_timeout	3600	Seconds before rsync aborts a stalled transfer

Requirements

• rsync
• ssh with key-based authentication (Generic only)
• POSIX-compatible shell (/bin/sh)
• find with -printf support (GNU findutils)