I recently had to move our Cacti install from a 32-bit to a 64-bit Linux system, and ran into the following RRD error:

ERROR: This RRD was created on another architecture

This is because the RRD file format is architecture-dependent, as described here. To convert all your Cacti RRD files, run the following on the 32-bit machine in your Cacti rra/ directory:

for i in `ls *. rrd`; do rrdtool dump $i > $i.xml; done

Next, transfer all the resulting .xml files to the new Cacti location’s rra/ directory on the 64-bit server, and run the following in the rra/ directory:

for i in `ls *.xml`; do rrdtool restore $i `echo $i |sed s/.xml//g`; done

This will regenerate all .rrd files using the data from the .xml files.