Efficient location of discrepancies in multiple replicated large files

We present a new technique for locating corrupted page copies, outdated page copies, and missing page copies in multiple replicated large file copies. We present four communication models and four communication protocols to be used in this technique. These four protocols are classified according to using or not using a coordinator site, groups, and/or a master signature. Whereas, other previous works consider locating only corrupted page copies, our protocols can locate outdated page copies and missing page copies as well as corrupted page copies. In addition, whereas other previous works are based on majority rule to determine the correct copy, our protocols are not. The performances of these protocols are measured in terms of the number of transmissions and the number of transmitted signatures. We compare these performances with one another and, also, compare them to the performances of other previous works