not affect global routing efficiency step 46 comprises a monitor of i o requests that are directed to the storage servers in the system similar i o patterns e g concurrent i o activity directed to two or more volumes are an indicator that the servers may contain similar data if concurrent i o activity is directed to n volumes they can be treated in pairs so that all n volumes are ultimately deduplicated for example if volumes a b and c are being evaluated it can first be determined that volumes a and b have similar i o patterns and then that volume c is similar to volumes a and or b as noted above step 46 and the subsequent steps shown herein need not be performed in the order presented in the example of fig4 the monitor may comprise subcombinations of the analysis steps described below indeed not all the steps may be performed in particular implementations moreover the examples of similarity metrics for i o requests cited herein are presented by way of example and not of limitation many other metrics of similarity will occur to those skilled in the art at decision step 48 it is determined if similar i o patterns exist e g i o requests that have been sent to two volumes at about the same time e g within a predetermined time interval that indicates concurrency of the two i o requests if the determination at decision step 48 is negative then monitoring continues at step 46 evaluation of similarity of the i o requests may consider the following information in the requests 1 read or write and 2 the logical offset in the volume for example similarity in the i o pattern is.