Method, apparatus and program storage device for maintaining data consistency and cache coherency during communications failures between nodes in a remote mirror pair

A data storage system, comprising:

• a first storage subsystem, the first storage subsystem comprising an array of drives;
• a second storage subsystem comprising an array of drives and having a mirrored volume set thereon of the volume set on the first storage subsystem;
• a first and second controller coupled respectively to the first and second storage subsystems;
• and
• a host, coupled to the first and second controllers, for issuing input/output requests to the first data storage system;
• wherein the first and second controller are coupled by a link, the first and second controller further being configured to monitor the link coupling the first storage system and the second storage system, during a link failure between the first storage system and the second storage systems, to independently perform reads and writes on the first and second storage systems and maintain write data and associated timestamps for the write data for each write in a queue of the first and second storage system and after link reestablishment, and to resynchronize volume sets on the first and second storage systems using the write data and associated timestamps.

A data processing apparatus, comprising:

• a memory comprising executable instructions;
• and
• a processor for executing instructions provided from the memory;
• wherein the processor is configured to perform the executable instructions from the memory to monitor a link to a second storage system, during a failure of the link, to independently perform reads and writes and maintain write data and timestamps associated with the write data for each write in the memory and, after link reestablishment, to resynchronize volume sets with the second storage system using the write data and associated timestamps.

A method for maintaining data consistency and cache coherency during communications failures between nodes in a remote mirror pair, the method comprising:

• monitoring a link between a mirror pair of storage systems, the mirror pair comprising a first storage system and a second storage system;
• during a link failure between the first storage system and the second storage systems, independently performing reads and writes on the first and second storage systems and maintaining write data and associated timestamps for the write data for each write in a queue of the first and second storage system;
• and
• after link reestablishment, resynchronizing volume sets on the first and second storage systems using the write data and associated timestamps.

A data storage system, comprising:

• a first storage means for storing a volume set thereon;
• a second storage means for providing a mirrored volume set thereon of the volume set on the first storage subsystem;
• means, coupled to the first and second storage means, for controlling the first and second storage means;
• and
• host means, coupled to the means for controlling, for issuing input/output requests to the first data storage system;
• wherein the means for controlling include linking means, the means for controlling further monitoring the linking means and, during a link failure between the first storage means and the second storage means, independently performing reads and writes on the first and second storage means and maintaining write data and associated timestamps for the write data for each write in a queue of the first and second storage means and after link reestablishment, and resynchronizing volume sets on the first and second storage means using the write data and associated timestamps.

A data processing apparatus, comprising:

• means for providing memory that includes executable instructions;
• and
• processing means for executing instructions provided from the means for providing memory;
• wherein the processing means is configured to perform the executable instructions from the means for providing memory for monitoring a link to a second storage means, during a failure of the link, independently performing reads and writes and maintaining write data and timestamps associated with the write data for each write in the means for providing memory and, after link reestablishment, resynchronizing volume sets with the second storage means using the write data and associated timestamps.