A method for tracking transactions performed on a non-volatile storage medium. The medium consists of a plurality of storage ranges. The method includes assigning respective local counters to the plurality of storage ranges, the local counters having respective local counter values, and storing the local counter values together in a selected region of the non-volatile storage medium. The method further includes updating the respective local counter values stored in the selected region responsively to the transactions performed on the storage ranges to which the local counters are respectively assigned. The method also includes reading and combining the local counter values from the selected region in order to determine a global counter value with respect to the non-volatile storage medium.