Exemple de réplication d’une jail en ZFS sur FreeBSD

L’environnement d’exemple est celui ou  j’ai divers web, blog, photos, etc., mais le même principe de réplication est utilisé à grande échelle pour un plan de continuité d’activité (PCA) entre des serveurs sur deux  centre de données différent avec des périodes de réplication adaptée aux besoins.

pour mon exemple, /etc/crontab

# chaque jour juste l’incrémental
45 4 * * * root (echo "Subject: ZFS replicate zsync_web incremental " && ( (/usr/bin/time -h /backup/zsync_web incremental) 2>&1 ) ) | sendmail -f FROM@DOMAIN TO@DOMAIN
# le 22 du mois, un full
10 4 22 * * root (echo "Subject: ZFS replicate zsync_web full " && ( (/usr/bin/time -h /backup/zsync_web full) 2>&1 ) ) | sendmail -f FROM@DOMAIN TO@DOMAIN

Je passe sur l’échange de clef SSH entre le host source et celui de destination pour faire la réplication via ssh, et j’utilise aussi shlock.

# pkg info | grep shlock
shlock-2.6.3 Create lock files for use in shell scripts

Le principe ZFS, un bookmark et des snapshot, du zfs send et receive entre deux serveurs.

La syntaxe:
/backup/zsync_web full|incremental|list|show

# /backup/zsync_web list
snapshot jails/web :
jails/web@L1_5 13.2M – 92.4G –
jails/web@L1_6 12.5M – 92.4G –
jails/web@L1_7 18.4M – 92.4G –
jails/web@L1_1 7.01M – 92.4G –
jails/web@L1_2 17.1M – 92.4G –
jails/web@L1_3 5.66M – 92.4G –
jails/web@L1_4 2.16M – 92.4G –
bookmark jails/web :
jails/web#L0_1_bookmark – – – –

Le script au complet:

# zsync / ZFS incremental backup réplication
# FreeBSD 12 - 2021-01 jcmichot _@_ free.org

# replicate/synchronize zfs file system on remote host

DAYWEEK=`date "+%u"`

# /!\ CHANGE "HOSTNAME" /!\ by your replication target hostname
MYTARGET="HOSTNAME"
# /!\ CHANGE "jail/web"/!\ by your source jail to replicate
MYFS="jails/web"
LOCK="/var/tmp/zsync_web.lock"

IGNORE=nozsync
CMD=$1

trap 'rm -f ${LOCK} ; exit 1' 1 2 3 15
if shlock -p $$ -f ${LOCK} ; then

 case $CMD in
  full)

   # dump 0 - full backup day

   # LOCAL: remove all MYFS zsync snapshots and bookmark 
   zfs list -t snapshot | grep -e "$MYFS@L1_" -e "$MYFS@L0_" | awk '{ printf("zfs destroy %s\n", $1 ); }' | sh 
   zfs list -t bookmark | grep "$MYFS#L0_" | awk '{ printf("zfs destroy %s\n", $1 ); }' | sh

   # REMOTE (TARGET), remove all MYFS zsync snapshots 
   REMOTESNAPS=`ssh root@$MYTARGET zfs list -H -t snapshot -o name | grep $MYFS@`
   PROCED="$IGNORE $REMOTESNAPS"
   for p in $PROCED
    do
      case $p in
          $IGNORE)
              ;;
          *)
              ssh root@$MYTARGET zfs destroy $p
              ;;
      esac
    done

   zfs snapshot $MYFS@L0_1
   zfs bookmark $MYFS@L0_1 $MYFS#L0_1_bookmark

   zfs send -cvV $MYFS@L0_1 | ssh root@$MYTARGET zfs receive -F $MYFS@L0_1
   zfs destroy $MYFS@L0_1

   for i in 1 2 3 4 5 6 7
    do
    zfs snapshot $MYFS@L1_$i
    done
  ;;

  incremental)

   zfs destroy $MYFS@L1_$DAYWEEK
   zfs snapshot $MYFS@L1_$DAYWEEK

   # REMOTE (TARGET), remove the DAYWEEK INCREMENTAL snapshot

   REMOTESNAPS=`ssh root@$MYTARGET zfs list -H -t snapshot -o name | grep $MYFS@L1_$DAYWEEK`
   PROCED="$IGNORE $REMOTESNAPS"
   for p in $PROCED
    do
      case $p in
          $IGNORE)
              ;;
          *)
              ssh root@$MYTARGET zfs destroy $p
              ;;
      esac
    done

   zfs send -cvV -i $MYFS'#L0_1_bookmark' $MYFS@L1_$DAYWEEK | ssh root@$MYTARGET zfs receive -F $MYFS@L1_$DAYWEEK
  ;;

  list)
   echo "snapshot $MYFS :";
   zfs list -t snapshot | grep -e $MYFS@L1_ -e $MYFS@L0_
   echo "bookmark $MYFS :";
   zfs list -t bookmark | grep -e $MYFS#

  ;;
  show)
   echo "no zsync running";
  ;;

  *)
   echo "unknown command"
   echo "$0 full|incremental|list|show";
  ;;

 esac

 rm -f ${LOCK}

else

 case $CMD in
  show)
   SPID=`cat ${LOCK}`
   top -ap $SPID
  ;;

  *)
   echo "zsync locked by `cat ${LOCK}`"
  ;;

 esac

 exit 0;

fi