add some improvements

libvirt-zsh-backup.sh

@@ -35,6 +35,8 @@ DATE=$(date "+%Y%m%d%H%M")
 DATE30=$(date -d "-30day" "+%Y%m%d")
 SNAPNAME="backup_$DATE"
 
+echo "$(date +%Y-%m-%d_%H:%M): Starting Backup of $VM"
+
 abortFunction()
 {
     zfs set backup:success="false" $SRCZFS
@@ -93,21 +95,32 @@ done
 virsh snapshot-delete $VM $SNAPNAME --metadata
 
 SUCCESS=$(zfs get backup:success -H -o value $SRCZFS)
+LASTBACKUP=$(zfs get backup:date -H -o value $SRCZFS)
 if [[ $SUCCESS == "true" ]]
 then
-    LASTBACKUP=$(zfs get backup:date -H -o value $SRCZFS)
     LASTSNAP="backup_$LASTBACKUP"
     echo "Sending incremental snapshot from $LASTSNAP"
     zfs send -R -i "$SRCZFS"@"$LASTSNAP" "$SRCZFS"@"$SNAPNAME" | pv -L $LIMIT | ssh $DESTHOST sudo zfs recv -F $DESTZFS
 else
-    echo "Sending full snapshot"
+    if [[ $LASTBACKUP != "-" ]]
-    zfs send -R "$SRCZFS"@"$SNAPNAME" | pv -L $LIMIT | ssh $DESTHOST sudo zfs recv -F $DESTZFS
+    then
+        LASTSNAP="backup_$LASTBACKUP"
+	echo "Trying to send incremental snapshot from $LASTSNAP"
+	zfs send -R -i "$SRCZFS"@"$LASTSNAP" "$SRCZFS"@"$SNAPNAME" | pv -L $LIMIT | ssh $DESTHOST sudo zfs recv -F $DESTZFS
+    else 
+        echo "Sending full snapshot"
+        zfs send -R "$SRCZFS"@"$SNAPNAME" | pv -L $LIMIT | ssh $DESTHOST sudo zfs recv -F $DESTZFS
+    fi
 fi
 if [ $? -eq 0 ]
 then
     zfs set backup:success="true" $SRCZFS
     zfs set backup:date="$DATE" $SRCZFS
-    zfs destroy "$SRCZFS"@"$LASTSNAP"
+    if [ -n $LASTSNAP ]
+    then
+	echo "Deleting old ZFS snapshot $LASTSNAP"
+        zfs destroy "$SRCZFS"@"$LASTSNAP"
+    fi
 else
     abortFunction
 fi