FusionSync and Core HA
We strongly recommend that you set up your Cores for HA. High-availability deployment provides for redundancy at the Core level within a single data center but not across data centers. Consider FusionSync as an enhancement to HA to protect against data center failures. Do not consider FusionSync as a replacement for HA within the data center. Core HA is active-active by design with each Core separately serving different sets of LUNs to their Edges. Therefore, each Core needs FusionSync configured for those LUNs to their replication peers.
When you have configured Core HA, one Core has the role of the leader and the other has the role of the follower.
Consider the following factors when configuring replication for Cores set up for HA:
• Some configuration changes are only possible on the leader Core. For example, suspend and failover operations are only allowed on the leader. If the leader is down, the follower Core assumes the role of leader.
• You need to configure the same Journal LUN on both the leader and the follower Cores.
• If the primary Core is set up for HA, the secondary Core must be configured for HA too.
• HA must be set up before configuring replication.
• Cores configured for HA must have the same replication role and data center name.
• After you have configured replication, you cannot clear the Core HA.
• When setting up the replication pair, both primary Cores in HA configuration need to be paired to their peers in the secondary data center. For example, Core X paired with Core X' and Core Y is paired with Y'.
• Terminating replication from the primary Core that is set up for HA terminates FusionSync for all four nodes.