Using rrdtool to monitor few servers

Question

Please help to understand. I find the simple of script in off site about update RRDTool base.

But for me need to create one rrd base to all servers. Please help to understand what way the best and just give some point how to do this. Send data from all servers to rrdtool base and update it? or try to get all data from server where rrdtool and update in local level?

 #!/bin/sh
 a=0
 while [ "$a" == 0 ]; do
 snmpwalk -c public 192.168.1.250 hrSWRunPerfMem > snmp_reply
     total_mem=`awk 'BEGIN {tot_mem=0}
                           { if ($NF == "KBytes")
                             {tot_mem=tot_mem+$(NF-1)}
                           }
                     END {print tot_mem}' snmp_reply`
     # I can use N as a replacement for the current time
     rrdtool update target.rrd N:$total_mem
     # sleep until the next 300 seconds are full
     perl -e 'sleep 300 - time % 300'
 done # end of while loop