Data transfer protocol for data replication between multiple pairs of storage controllers on a san fabric

A method of communicating between storage controllers in a storage area network, comprising:

• receiving a host command to create a data replication group;
• creating a local group object in a first controller;
• building a tunnel connecting the first controller and a second controller through a communication fabric;
• creating a remote group object in the second controller;
• and
• aggregating a plurality of commands or a plurality of responses from the first controller or the second controller, or both, into a single buffer resource in the first controller, the second controller, or both.

A system for performing transactions in a storage area network (SAN) comprising:

• at least two storage sites coupled by a fibre channel fabric, wherein at least one sending controller is configured to send a group of frames to at least one receiving controller that is configured to receive the group of frames,
• and a non-transitory computer readable medium comprising a protocol, wherein the protocol comprises:
• a first protocol mechanism for sending unsolicited frames including data operations and command operations from a sending controller to a receiving controller;
• a second protocol mechanism for sending unsolicited heartbeat messages from the sending controller to the receiving controller;
• and
• a third protocol mechanism operable on the receiving controller to determine from the heartbeat message when an operation has not been received;
• and
• wherein the protocol is configured to aggregate a plurality of the data operations or a plurality of the command operations in a single buffer.

A method for building a tunnel to establish a data replication group between a pair of storage controllers on a storage area network, the method comprising:

• receiving, in a first storage controller, a host command to create a data replication group;
• creating a local group object representing one or more virtual disks in the first storage controller;
• building an I/O tunnel connecting the first storage controller and a second storage controller through a fibre channel fabric, wherein and building the I/O tunnel comprises:
• allocating one or more buffer resources to be utilized by the I/O tunnel for data transaction at the first storage controller;
• sending a create tunnel command from the first storage controller to the second storage controller;
• allocating one or more buffer resources to be utilized by the I/O tunnel for data transaction at the second storage controller upon receiving the create tunnel command;
• receiving a created tunnel message at the first storage controller indicating successful creation of the I/O tunnel and identity of the buffer resources allocated at the second storage;
• and
• sending a protocol message by the first storage controller through the I/O tunnel to the second storage controller causing the second storage controller to create a remote group object representing one or more virtual disks in the second storage controller;
• and
• automatically deallocating one or more of the buffer resources upon completion of the data transaction.