A cluster can have a Metro Mirror and Global Mirror cluster partnership with one or more other clusters. Partnership sets consist of clusters that are either in direct partnership with each other or are in indirect partnership by having a partnership with the same intermediate cluster. The topology of the partnership set is not fixed; the topology might be a star, a loop, a chain or a mesh. The maximum supported number of clusters in a partnership set is four. A cluster is a member of a partnership set if it has a partnership with another cluster in the set, regardless of whether that partnership has any defined consistency groups or relationships.
These are examples of valid partnership sets for five unique clusters labelled A, B, C, D, and E where a partnership is indicated by a dash between two cluster names:
These are examples of unsupported configurations because the number of clusters in the set is five, which exceeds the supported maximum of four clusters:
The cluster prevents you from creating a new Metro Mirror and Global Mirror cluster partnership if a resulting partnership set would exceed the maximum of four clusters. However, if you restore a broken link between two clusters that have a partnership, the number of clusters in the set might exceed four. If this occurs, Metro Mirror and Global Mirror cluster partnerships are excluded from the set until only four clusters remain in the set. A cluster partnership that is excluded from a set has all of its Metro Mirror and Global Mirror cluster partnerships excluded.
Event ID 0x050030 is reported if the cluster is retained in the partnership set. Event ID 0x050031 is reported if the cluster is excluded from the partnership set. All clusters that were in the partnership set report error 1710.
All inter-cluster Metro Mirror or Global Mirror relationships that involve an excluded cluster will lose connectivity. If any of these relationships are in the consistent_synchronized state and they receive a write I/O, they will stop with error code 1720.
To fix this error it is necessary to delete all of the relationships that could not be recovered and then re-create the relationships.
Possible Cause-FRUs or other: