Bidirectional Replication

A storage array, comprising:

• a number of storage devices;
• and
• a storage controller comprising processing circuitry and a cache;
• wherein the storage controller is to:
• participate in implementing replication from a first LUN of an other storage array as a primary LUN to a second LUN of the storage array as a secondary LUN;
• and
• in response to receiving from a host a write that is directed to the second LUN:
• send write data of the write to the other storage array while maintaining a copy of the write data in a fenced portion of the cache;
• and
• wait to release the copy of the write data to the second LUN until a write acknowledgment is received from the other storage array.

A non-transitory machine readable medium comprising processor-executable instructions for implementing bidirectional replication between a primary LUN of a first storage array and a secondary LUN of a second storage array, including:

• instructions to, in response to the second storage array receiving from a host a write that is directed to the secondary LUN, cause the second storage array to:
• send write data of the write to the first storage array while maintaining a copy of the write data in a fenced portion of a cache of the second storage array;
• and
• wait to release the copy of the write data to the secondary LUN until a write acknowledgment is received from the first storage array.