Fibre Channel Storage Array Methods for Handling Cache-Consistency Among Controllers of an Array and Consistency Among Arrays of a Pool

A storage array, comprising,

• (a) an active controller configured to execute a primary process and a first secondary process,
• (i) the primary process includes a volume manager and a first SCSI layer;
• (ii) the first secondary process includes a second SCSI layer;
• and
• (iii) a first logical unit (LU) cache, the first LU cache configured to store configuration data related to logical unit number (LUN) mapping and port data;
• (b) a standby controller configured to execute a second secondary process,
• (i) the second secondary process includes a third SCSI layer;
• (ii) a second logical unit (LU) cache, the second LU cache is also configured to store the configuration data related to logical unit number (LUN) mapping and port data;
• and
• (c) a configuration management unit that is configured to communicate changes to the configuration data to the primary process, the primary process is configured to push said changes to the configuration data to said second secondary process to enable commitment to said second LU cache, wherein the primary process of the active controller is configured to wait to commit the changes to the configuration data to the first LU cache until confirmation is received by the primary process that the second secondary process has committed the changes to the configuration data to the second LU cache;
• wherein the storage array is configured to service requests from one or more initiators.

A storage array, comprising,

• an active controller configured to execute a primary process that includes a volume manager and a first SCSI layer, the active controller further includes a first logical unit (LU) cache for storing configuration data related to logical unit number (LUN) mapping and port data of the storage array;
• a standby controller configured to execute a secondary process (280b), the secondary process includes a second SCSI layer, the standby controller further includes a second logical unit (LU) cache that is also configured to store the configuration data related to logical unit number (LUN) mapping and port data of the storage array;
• and
• a configuration management unit that is configured to communicate changes to the configuration data to the primary process, the primary process is configured to push said changes to the configuration data to said secondary process to enable commitment to said second LU cache,
• wherein the primary process of the active controller is configured to wait to commit the changes to the configuration data to the first LU cache until confirmation is received by the primary process that the secondary process has committed the changes to the configuration data to the second LU cache;
• wherein the storage array is configured to service requests from one or more initiators.

Computer readable media, being non-transitory, for maintaining consistency in configuration data between processes running on an active controller and a standby controller of a storage array, comprising,

• program instructions for executing a primary process in user space of the active controller, the primary process configured to process request commands from one or more initiators, the primary process having access to a volume manager for serving data input/output (I/O) requests and non-I/O requests, the primary process having primary access to the configuration data and having a first logical unit (LU) cache for storing the configuration data;
• program instructions for executing a secondary process in user space of the standby controller, the secondary process configured to process request commands from one or more of the initiators, the secondary process not having access to the volume manger, the secondary process having a second LU cache for storing the configuration data, the second LU cache being used by the secondary process for responding to non-I/O requests;
• program instructions for receiving, at the primary process, an update to the configuration data;
• program instructions for sending, by the primary process, the update to the configuration data to the secondary process for updating the second LU cache, and if the primary process receives an acknowledgement from the secondary process that the update to the configuration data was received, then committing the updates to the configuration data to the first LU cache of the active controller.