Long-distance requirements for partnerships
The links between systems in a partnership that are used for replication must meet specific configuration, latency, and distance requirements.
The following table lists the maximum round-trip latency for each type of partnership.
Table 1. Maximum supported round-trip latency between sites Partnership FC IP 250 ms 80 ms - Replication requires a specific amount of bandwidth for intersystem heartbeat traffic. When the
system uses a Fibre Channel partnership, the amount of traffic depends on the number of nodes that
are in both the local system and the remote system. Table 2 provides a
guideline for the intersystem heartbeat traffic between the systems. These numbers represent the
total traffic between two systems when no I/O operations run on the copied volumes. Half of the data
is sent by the local system and half of the data is sent by the remote system. Therefore, traffic is
evenly divided between all of the available intersystem links. If you have two redundant links, half
of the traffic is sent over each link.
Table 2. Intersystem heartbeat traffic in Mbps System 1 System 2 2 nodes 4 nodes 6 nodes 8 nodes 2 nodes 5 6 6 6 4 nodes 6 10 11 12 6 nodes 6 11 16 17 8 nodes 6 12 17 21 - If the link between two sites is configured with redundancy so that it can tolerate single failures, the link must be sized so that the bandwidth and latency statements are correct during single failure conditions.