You may want to monitor the speed of a current snapmirror to get an idea of how fast the transfer is going. The speed might change throughout the day due to load, or disk bottleneck, etc. I started with this one-liner:

i=0;j=0; while true; do j=$i; i=`ssh toaster01 "snapmirror status -l volname" | grep Progress | awk '{print $2}'| cut -d \( -f2`; if [ $j -eq 0 ]; then sleep 1m; continue; fi; echo -n "$i-$j = ";echo "scale=2;($i-$j)/(1024*1024)" | bc | tr '\n' ' '; echo "GB/min"; sleep 1m; done;

Which lead to this short script:

#!/bin/bash
# FILE: netapp_sm_monitor.sh
# AUTHOR: For Do Done <fordodone@fordodone.com>
# DATE: 2014/03/26
# NOTES: 
# 

if [ $# -lt 2 ]
then
  echo ""
  echo "usage: netapp_sm_monitor.sh <filer> <srcvol> [-v]"
  echo ""
  exit
fi

i=0;
j=0; 

while true; 
do 
  j=$i; 
  i=`ssh $1 "snapmirror status -l $2" | grep Progress | awk '{print $2}'| cut -d \( -f2`; 
  if [ $j -eq 0 ]; 
    then 
    sleep 1m; 
    continue; 
  fi; 
  if [ "$3" == "-v" ]
  then
    echo -n "$i-$j = ";
  fi
  echo "scale=2;($i-$j)/(1024*1024)" | bc | tr '\n' ' '; echo "GB/min"; 
  sleep 1m; 
done;