Sync a bunch of zfs volumes to a remote (designed to be called from a cron-like system)

zfs-sync-to-remote.sh

#!/bin/bash
##
# https://gist.githubusercontent.com/ertug/1087896/raw/0ff791dce616993f8557bf74e1f47cebb4b69aae/zfs-snapshot.sh
# original code: http://andyleonard.com/2010/04/07/automatic-zfs-snapshot-rotation-on-freebsd/
# 07/17/2011 - ertug: made it compatible with zfs-fuse which doesn't have .zfs directories
##

# Path to ZFS executable:
ZFS=/sbin/zfs

SETTINGS=/root/zfs.sync
SVOLUMES=$SETTINGS/volumes
DESTHOST=$(cat $SETTINGS/dest-host)
HOSTPOOL=$(cat $SETTINGS/host-pool)
DESTPOOL=$(cat $SETTINGS/dest-pool)
VOLUMES=$(cd $SVOLUMES; ls)

if [ -z "$HOSTPOOL" ] || [ -z "$VOLUMES" ] || [ -z "$DESTHOST" ] || [ -z "$DESTPOOL" ]; then
    (
    echo "$0: incomplete configuration"
    echo "dest: $DESTHOST"
    echo "  pool: $DESTPOOL"
    echo "pool: $HOSTPOOL"
    echo "  volumes: $VOLUMES"
    ) >&2
    exit 1
fi

for a in $VOLUMES; do
  NEXTSNAP=$(date +%Y%m%d%H%M)
  VOLUME=$(cat $SVOLUMES/$a/vol)
  zfs snapshot -r $HOSTPOOL/$VOLUME@$NEXTSNAP
  PREVSNAP=$(cat $SVOLUMES/$a/prev-snap 2>/dev/null)
  LASTSNAP=$(cat $SVOLUMES/$a/last-snap)
  if [ -z "$LASTSNAP" ] || [ "$PREVSNAP" = "$LASTSNAP" ]; then
      (
      echo "$0: invalid volume settings"
      echo "pool: $HOSTPOOL"
      echo "  volume: $VOLUME"
      echo "prevsnap: $PREVSNAP"
      echo "lastsnap: $LASTSNAP"
      echo "... ignoring prevsnap"
      ) >&2
      PREVSNAP=
  fi

  mv -f $SVOLUMES/$a/last-send.log $SVOLUMES/$a/prev-send.log
  mv -f $SVOLUMES/$a/last-send.err $SVOLUMES/$a/prev-send.err

  if zfs send -Rci @$LASTSNAP $HOSTPOOL/$VOLUME@$NEXTSNAP |
    ssh $DESTHOST zfs recv -Fduv $DESTPOOL > $SVOLUMES/$a/last-send.log 2> $SVOLUMES/$a/last-send.err; then
    mv $SVOLUMES/$a/last-snap $SVOLUMES/$a/prev-snap
    echo "$NEXTSNAP" > $SVOLUMES/$a/last-snap
    if [ ! -z "$PREVSNAP" ]; then
      zfs destroy -r $HOSTPOOL/$VOLUME@$PREVSNAP
      ssh $DESTHOST zfs destroy -r $DESTPOOL/$VOLUME@$PREVSNAP
    fi
    true
  else
    LASTERR=$?
    (
    echo "$0: send $VOLUME failed..."
    echo "zfs send -Rci @$LASTSNAP $HOSTPOOL/$VOLUME@$NEXTSNAP | ssh $DESTHOST zfs recv -Fduv $DESTPOOL"
    echo "output:"
    cat $SVOLUMES/$a/last-send.log
    echo "error:"
    cat $SVOLUMES/$a/last-send.err
    echo "exit: $LASTERR"
    ) >&2
  fi
done