diff --git a/extra/resources/ClusterMon.in b/extra/resources/ClusterMon.in
index 27cbb98c3d..e560ed4e4a 100755
--- a/extra/resources/ClusterMon.in
+++ b/extra/resources/ClusterMon.in
@@ -1,267 +1,267 @@
 #!@BASH_PATH@
 #
 # ocf:pacemaker:ClusterMon resource agent
 #
 # Original copyright 2004 SUSE LINUX AG, Lars Marowsky-Br<E9>e
 # Later changes copyright 2008-2021 the Pacemaker project contributors
 #
 # The version control history for this file may have further details.
 #
 # This source code is licensed under the GNU General Public License version 2
 # (GPLv2) WITHOUT ANY WARRANTY.
 #
 
 # Starts crm_mon in background which logs cluster status as
 # html to the specified file.
 
 #######################################################################
 # Initialization:
 : ${OCF_FUNCTIONS:="${OCF_ROOT}/resource.d/heartbeat/.ocf-shellfuncs"}
 . "${OCF_FUNCTIONS}"
 : ${__OCF_ACTION:="$1"}
 
 # Explicitly list all environment variables used, to make static analysis happy
 : ${OCF_RESKEY_user:=""}
 : ${OCF_RESKEY_pidfile:="/tmp/ClusterMon_${OCF_RESOURCE_INSTANCE}.pid"}
 : ${OCF_RESKEY_update:="15000"}
 : ${OCF_RESKEY_extra_options:=""}
 : ${OCF_RESKEY_htmlfile:="/tmp/ClusterMon_${OCF_RESOURCE_INSTANCE}.html"}
 
 #######################################################################
 
 meta_data() {
     cat <<END
 <?xml version="1.0"?>
 <resource-agent name="ClusterMon" version="1.1">
 <version>1.1</version>
 
 <longdesc lang="en">
 This is a ClusterMon Resource Agent.
 It outputs current cluster status to the html.
 </longdesc>
 <shortdesc lang="en">Runs crm_mon in the background, recording the cluster status to an HTML file</shortdesc>
 
 <parameters>
 
 <parameter name="user">
 <longdesc lang="en">
 The user we want to run crm_mon as
 </longdesc>
 <shortdesc lang="en">The user we want to run crm_mon as</shortdesc>
 <content type="string" default="root" />
 </parameter>
 
 <parameter name="update">
 <longdesc lang="en">
 How frequently should we update the cluster status (in milliseconds).
 For compatibility with old documentation, values less than 1000 will be treated
 as seconds.
 </longdesc>
 <shortdesc lang="en">Update interval in milliseconds</shortdesc>
 <content type="integer" default="15000" />
 </parameter>
 
 <parameter name="extra_options">
 <longdesc lang="en">
 Additional options to pass to crm_mon.  Eg. -n -r
 </longdesc>
 <shortdesc lang="en">Extra options</shortdesc>
 <content type="string" default="" />
 </parameter>
 
-<parameter name="pidfile">
+<parameter name="pidfile" unique-group="pidfile">
 <longdesc lang="en">
 PID file location to ensure only one instance is running
 </longdesc>
 <shortdesc lang="en">PID file</shortdesc>
 <content type="string" default="/tmp/ClusterMon_${OCF_RESOURCE_INSTANCE}.pid" />
 </parameter>
 
-<parameter name="htmlfile" required="0">
+<parameter name="htmlfile" unique-group="htmlfile" required="0">
 <longdesc lang="en">
 Location to write HTML output to.
 </longdesc>
 <shortdesc lang="en">HTML output</shortdesc>
 <content type="string" default="/tmp/ClusterMon_${OCF_RESOURCE_INSTANCE}.html" />
 </parameter>
 </parameters>
 
 <actions>
 <action name="start"   timeout="20s" />
 <action name="stop"    timeout="20s" />
 <action name="monitor" depth="0"  timeout="20s" interval="10s" />
 <action name="meta-data"  timeout="5s" />
 <action name="validate-all"  timeout="30s" />
 </actions>
 </resource-agent>
 END
 }
 
 #######################################################################
 
 ClusterMon_usage() {
     cat <<END
 usage: $0 {start|stop|monitor|validate-all|meta-data}
 
 Expects to have a fully populated OCF RA-compliant environment set.
 END
 }
 
 ClusterMon_exit() {
     if [ $1 -ne 0 ]; then
         exit $OCF_ERR_GENERIC
     else
         exit $OCF_SUCCESS
     fi
 }
 
 ClusterMon_start() {
     if [ -n "$OCF_RESKEY_user" ]; then
         su - "$OCF_RESKEY_user" -c "$CMON_CMD"
     else
         eval $CMON_CMD
     fi
     ClusterMon_exit $?
 }
 
 ClusterMon_stop() {
     if [ -f "$OCF_RESKEY_pidfile" ]; then
         pid=$(cat "$OCF_RESKEY_pidfile")
         if [ -n "$pid" ]; then
             kill -s 9 $pid
             rm -f "$OCF_RESKEY_pidfile"
         fi
     fi
     ClusterMon_exit 0
 }
 
 ClusterMon_monitor() {
     local USERARG=""
     local header
     local pid
 
     if [ -f "$OCF_RESKEY_pidfile" ]; then
         pid=$(cat "$OCF_RESKEY_pidfile")
         if [ -n "$pid" ]; then
             if [ -n "$OCF_RESKEY_user" ]; then
                 USERARG="-u $OCF_RESKEY_user"
             fi
 
             # Use column header wide as command, to ensure it's shown in full
             header=$(echo $CMON_CMD | tr 'crmon, \t' 'xxxxxxxx')
 
             ps $USERARG -o "args=${header}" -p $pid 2>/dev/null | \
                 grep -qE "[c]rm_mon.*${OCF_RESKEY_pidfile}"
 
             case $? in
                 0) exit $OCF_SUCCESS;;
                 1) exit $OCF_NOT_RUNNING;;
                 *) exit $OCF_ERR_GENERIC;;
             esac
         fi
     fi
     exit $OCF_NOT_RUNNING
 }
 
 CheckOptions() {
 while getopts Vi:nrh:cdp: OPTION
 do
     case "$OPTION" in
     V|n|r|c|d);;
     i)  ocf_log warn "You should not have specified the -i option, since OCF_RESKEY_update is set already!";;
     h)  ocf_log warn "You should not have specified the -h option, since OCF_RESKEY_htmlfile is set already!";;
     p)  ocf_log warn "You should not have specified the -p option, since OCF_RESKEY_pidfile is set already!";;
     *)  return $OCF_ERR_ARGS;;
     esac
 done
 
 if [ $? -ne 0 ]; then
     return $OCF_ERR_ARGS
 fi
 
 # We should have eaten all options at this stage
 shift $(($OPTIND -1))
 if [ $# -gt 0 ]; then
     false
 else
     true
 fi
 }
 
 ClusterMon_validate() {
 # Existence of the user
     if [ -n "$OCF_RESKEY_user" ]; then
         getent passwd "$OCF_RESKEY_user" >/dev/null
         if [ $? -eq 0 ]; then
             : Yes, user exists. We can further check his permission on crm_mon if necessary
         else
             ocf_log err "The user $OCF_RESKEY_user does not exist!"
             exit $OCF_ERR_ARGS
         fi
     fi
 
 # Pidfile better be an absolute path
     case "$OCF_RESKEY_pidfile" in
         /*) ;;
         *) ocf_log warn "You should have pidfile($OCF_RESKEY_pidfile) of absolute path!" ;;
     esac
 
 # Check the update interval
     if ocf_is_decimal "$OCF_RESKEY_update" && [ $OCF_RESKEY_update -gt 0 ]; then
         :
     else
         ocf_log err "Invalid update interval $OCF_RESKEY_update. It should be positive integer!"
         exit $OCF_ERR_ARGS
     fi
 
     if CheckOptions $OCF_RESKEY_extra_options; then
         :
     else
         ocf_log err "Invalid options $OCF_RESKEY_extra_options!"
         exit $OCF_ERR_ARGS
     fi
 
 # Htmlfile better be an absolute path
     case "$OCF_RESKEY_htmlfile" in
         /*) ;;
         *) ocf_log warn "You should have htmlfile($OCF_RESKEY_htmlfile) of absolute path!" ;;
     esac
 
     echo "Validate OK"
     return $OCF_SUCCESS
 }
 
 if [ $# -ne 1 ]; then
     ClusterMon_usage
     exit $OCF_ERR_ARGS
 fi
 
 if [ ${OCF_RESKEY_update} -ge 1000 ]; then
     OCF_RESKEY_update=$(( $OCF_RESKEY_update / 1000 ))
 fi
 
 CMON_CMD="${HA_SBIN_DIR}/crm_mon -p \"$OCF_RESKEY_pidfile\" -d -i $OCF_RESKEY_update $OCF_RESKEY_extra_options -h \"$OCF_RESKEY_htmlfile\""
 
 case "$__OCF_ACTION" in
 meta-data)      meta_data
                 exit $OCF_SUCCESS
                 ;;
 start)          ClusterMon_start
                 ;;
 stop)           ClusterMon_stop
                 ;;
 monitor)        ClusterMon_monitor
                 ;;
 validate-all)   ClusterMon_validate
                 ;;
 usage|help)     ClusterMon_usage
                 exit $OCF_SUCCESS
                 ;;
 *)              ClusterMon_usage
                 exit $OCF_ERR_UNIMPLEMENTED
                 ;;
 esac
 
 exit $?
 
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