ZFS and Backups Revision as of Wednesday, 25 December 2019 at 06:49 UTC

Backup all datasets and snapshots in a Zpool to an external USB drive. This person has basically the same approach except that they’re doing it via manual cron job.

#!/usr/local/bin/bash

# Run this as root. Get weird errors with zfs not being able to unmount
# before receiving snapshots :/

SOURCE_POOL="source"
DESTINATION_POOL="backup"
SNAPSHOT_LABEL="manual_monthly_backup"
SNAPSHOT_LABEL_PREV="${SNAPSHOT_LABEL}_previous"

# --- Initial Backup ---

# First, take a snapshot of the pool to back up
# I have underlying underlying datasets, so make this recursive
zfs snapshot -r "$SOURCE_POOL@$SNAPSHOT_LABEL"

# Initial transfer. `pv` shows progress nicely. We
# are backing up all datasets and their snapshots.
zfs send -R "$SOURCE_POOL@$SNAPSHOT_LABEL" | pv | zfs receive -vF $DESTINATION_POOL

# --- All subsequent backups ---

# Incremental backups! First, rename the old
zfs rename -r $SOURCE_POOL@$SNAPSHOT_LABEL $SOURCE_POOL@$SNAPSHOT_LABEL_PREV

# Take a fresh new snapshot
zfs snapshot -r $SOURCE_POOL@$SNAPSHOT_LABEL

# Send incrementals to the destination. The `-i` flag
# will send the difference between the two arguments to
# the destination.
#
# If all intermediary snapshots are required, use '-I'
zfs send -R -i $SOURCE_POOL@$SNAPSHOT_LABEL_PREV $SOURCE_POOL@$SNAPSHOT_LABEL | pv | zfs receive -v $DESTINATION_POOL

# Don't need the previous snapshots anymore... clean up
zfs destroy -r $SOURCE_POOL@$SNAPSHOT_LABEL_PREV
zfs destroy -r $DESTINATION_POOL@$SNAPSHOT_LABEL_PREV

cron Job

From that forum post up top:

(
    zfs rename -r mainpool@offsite-backup-new mainpool@offsite-backup-old;
    zfs snapshot -r mainpool@offsite-backup-new;
    zfs send -Ri mainpool@offsite-backup-old mainpool@offsite-backup-new | zfs recv -vFdu usbdrivepool;
    zfs destroy -r mainpool@offsite-backup-old;
    zfs destroy -r usbdrivepool@offsite-backup-old;
) | mail -s "FreeNAS Replication to USB Drive" "myemail@example.com"