A storage system comprises a plurality of storage subsystems. One storage subsystem as a succeeding subsystem is configured to receive and store one or more blocks of data from another storage subsystem as a preceding subsystem. Each block of data has an associated sequence number in ascending order. The memory in each storage subsystem includes a queue to store the blocks of data and a sequence number associated with each block of data, a record to store a last sequence number associated with a last block of data received by the queue, and a table to store last sequence numbers stored in the last sequence number record gathered from each succeeding storage system. In some embodiments, a smallest last sequence number is determined from the last sequence numbers associated with the blocks of data in the storage subsystems. Blocks of data in the queue of each storage subsystem having associated sequence numbers less than or equal to the determined smallest last sequence number are deleted. In case of a failure of one or more storage subsystems, blocks of data are copied from the surviving storage subsystem having associated sequence numbers higher than the last sequence number of other surviving storage subsystems.