implemented sync mode

zfs-backup.sh

@@ -76,6 +76,8 @@ function backup() {
 	R_SNAPSHOTS=( $(${R_RMOD} zfs list -rt snapshot -d1 -Ho name -S creation ${SAVETO}/$( basename ${DATASET}) 2>/dev/null) )
 	check_dataset ${SAVETO}/$( basename ${DATASET}) && R_USED_BEFORE=$(snapuse ${SAVETO}/$( basename ${DATASET}))
 
+	if [ ${MODE:-backup} == "backup" ]
+		then
 			# determine current timestamp
 			DATE=$(date +%Y-%m-%d-%H%M)
 
@@ -84,6 +86,7 @@ function backup() {
 
 			# take a snapshot
 			zfs snapshot -r ${NEWSNAP}
+	fi
 	
 	# check if source is encrypted
 	if [ $ENCRYPTION_FEATURE != "disabled" ]
@@ -107,22 +110,32 @@ function backup() {
 											if [ ${#R_SNAPSHOTS[*]} -ge 1 ]
 												then
 													# remote snapshot(s) found
-																		R_SNAPMODIFIER="I $(dirname ${DATASET})/$(basename ${R_SNAPSHOTS[*]:(-1)})"
+													R_SNAPMODIFIER="I $(dirname ${DATASET})/$(basename ${R_SNAPSHOTS[0]})"
 											fi
 											# send any previous snapshots
 											zfs send -Rcv${RAW_MOD}${R_SNAPMODIFIER} ${LASTSNAP} | ${RMOD:-$R_RMOD} zfs recv -Feu${RESUME_MOD}v ${SAVETO} 2>&1 >> ${LOGFILE}
+											if [[ ${PIPESTATUS[*]} =~ [1-9]+ ]]
+												then
+													# replication failure
+													logger -t $(basename ${0%.sh}) -p user.notice "failed to replicate ${LASTSNAP} to ${TARGET:-local}:${SAVETO}"
+												else
+													let CHANGES++
+											fi
 										}
 		else
 			# ensure this does not remain in effect
 			unset SNAPMODIFIER R_SNAPMODIFIER
 	fi
 	
+	if [ ${MODE:-backup} == "backup" ]
+		then
 			# send backup
 			zfs send -Rcv${RAW_MOD}${SNAPMODIFIER} ${NEWSNAP} | ${RMOD:-$R_RMOD} zfs recv -Feu${RESUME_MOD}v ${SAVETO} 2>&1 >> ${LOGFILE}
 
 			# if replication is unsuccessful, omit the aging check so as to prevent data loss
-	if [ $? -eq 0 ]
+			if [[ ! ${PIPESTATUS[*]} =~ [1-9]+ ]]
 				then
+					let CHANGES++
 					THRESHOLD=$(( $KEEP * 24 * 3600 ))
 					for SNAPSHOT in ${SNAPSHOTS[*]}
 						do
@@ -135,8 +148,8 @@ function backup() {
 							fi
 						done
 				else
-			MY_EXIT_CODE=$?
+					logger -t $(basename ${0%.sh}) -p user.notice "failed to replicate ${NEWSNAP} to ${TARGET:-local}:${SAVETO}, no aging"
-			logger -t $(basename ${0%.sh}) -p user.notice "failed to replicate ${NEWSNAP} (rc: $MY_EXIT_CODE) to ${TARGET:-local}:${SAVETO}, no aging"
+			fi
 	fi
 
 	# re-evaluate snapshot data usage
@@ -148,6 +161,9 @@ function backup() {
 			R_RMOD="ssh ${USER}@${TARGET}"
 	fi
 			
+	if [ ${CHANGES:-0} -gt 0 ]
+		then
+			# calculate data volume change
 			R_USED_AFTER=$(snapuse ${SAVETO}/$( basename ${DATASET}))
 			L_DELTA=$(( $L_USED_AFTER - $L_USED_BEFORE ))
 			R_DELTA=$(( $R_USED_AFTER - ${R_USED_BEFORE:-0} ))
@@ -176,6 +192,7 @@ function backup() {
 							logger -t $(basename ${0%.sh}) -p user.notice "$_DELTA ${WHAT:-allocated} in \"${WHERE}\" by backing up \"${DATASET}\""
 					fi
 				done
+	fi
 
 	# reset remote configuration
 	unset R_RMOD RMOD RAW_MOD
@@ -185,7 +202,7 @@ function backup() {
 
 #### BEGIN LOGIC ####
 
-while getopts hf:m: OPTION
+while getopts hf:m:s OPTION
 	do
 		case "$OPTION" in
 			f)
@@ -198,6 +215,11 @@ while getopts hf:m: OPTION
 				RECIPIENT="$OPTARG"
 				;;
 
+			s)
+				# sync mode | this could also be a per-target setting to mitigate the need to call multiple jobs
+				MODE="sync"
+				;;
+
 			h|\?)
 				# display help
 				usage
@@ -280,6 +302,7 @@ while read -u 4 DATASET SAVETO KEEP ENABLED
 		let COUNTER++
 		if [ ${ENABLED} == "Y" ]
 			then
+				# split this function -> snapshot(), sync(), age() ? -> a new backup() would call all three
 				backup
 		fi
 	done 4<<< "$(egrep -v '^(#|$)' "${CFGFILE}")" # graciously overlook any comments or blank lines