Method and Apparatus for Identifying a Device Missing from a Consistency Group

A consistency group is defined to include a set of required devices on a set of storage systems. Write patterns on each of the required devices are monitored and write patterns on each of the other devices on the set of storage systems is monitored. Pairs of devices are formed, in which each pair includes one required device and one other device. Write patterns of the pairs of devices are compared to determine respective percentage coordinated write probabilities for pairs of devices. Write patterns of the pairs of devices are also compared to determine ratios of write operations for pairs of devices. A coordinate write probability above a threshold, or a determined ratio of write operations that occurs sufficiently frequently, is interpreted as an indication that one of the other devices should be included in the consistency group. A learning process is trained and used to analyze the write patterns.