Do you have of the archive downloaded in the same folder? How to merge .part files using WinRar
Depending on where you obtained the file, "Cassandra" typically refers to: Cassandra.part3.rar
: You only need to right-click the first volume (usually ending in .part1.rar or just .rar ) and select "Extract Here" or "Extract Files". Do you have of the archive downloaded in the same folder