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

Abstract

Storage arrays, systems and methods for operating storage arrays for maintaining consistency in configuration data between processes running on an active controller and a standby controller of the storage array are provided. One example method includes executing a primary process in user space of the active controller. The primary process is configured to process request commands from one or more initiators, and the primary process has access to a volume manager for serving data input/output (I/O) requests and non-I/O requests. The primary process has primary access to the configuration data and includes a first logical unit (LU) cache for storing the configuration data. The method also includes executing a secondary process in user space of the standby controller. The secondary process is configured to process request commands from one or more of the initiators, wherein the secondary process does not have access to the volume manger. The secondary process has a second LU cache for storing the configuration data, and the second LU cache is used by the secondary process for responding to non-I/O requests. The method includes receiving, at the primary process, an update to the configuration data and sending, by the primary process, the update to the configuration data to the secondary process for updating the second LU cache. When the primary process receives an acknowledgement from the secondary process that the update to the configuration data was received, then the updates to the configuration data are committed to the first LU cache of the active controller.

Description

CLAIM OF PRIORITY[0001]This application claims priority from U.S. Provisional Patent Application No. 62 / 050,680, filed on Sep. 15, 2014, entitled “Fibre Channel Storage Array Systems and Methods,” which is herein incorporated by reference.BACKGROUND[0002]1. Field of the Invention[0003]The present embodiments relate to storage arrays, methods, systems, and programs for maintaining a consistent cache of logical unit data and port data for Fibre Channel arrays, such as where storage arrays use fail-over processes and standby hardware to maintain high availability to initiators.[0004]2. Description of the Related Art[0005]Network storage, also referred to as network storage systems or storage systems, is computer data storage connected to a computer network providing data access to heterogeneous clients. Typically network storage systems process a large amount of Input / Output (I / O) requests, and high availability, speed, and reliability are desirable characteristics of network storage.[...

AI Technical Summary

Benefits of technology

[0010]In one embodiment, a method for operating a storage array for maintaining consistency in configuration data between processes running on an active controller and a standby controller of the storage array is provided. In this embodiment, the method includes executing a primary process in user space of the active controller. The primary process is configured to process request commands from one or more initiators, and the primary process has access to a volume manager for serving data input / output (I / O) requests and non-I / O requests. The primary process has primary access to the configuration data and includes a first logical unit (LU) cache for storing the configuration data. The method also includes executing a secondary process in user space of the standby controller. The secondary process is configured to process request commands from one or more of the initiators, wherein the secondary process does not have access to the volume manger. The secondary process has a second LU cache for storing the configuration data, and the second LU cache is used by the secondary process for responding to non-I / O requests. The method includes receiving, at the primary process, an update to the configuration data and sending, by the primary process, the update to the configuration data to the secondary process for updating the second LU cache. When the primary process receives an acknowledgement from the secondary process that the update to the configuration data was received, then the updates to the configuration data are committed to the first LU cache of the active controller.

[0011]In another embodiment, a storage array is provided. The storage array includes 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. Further included is a standby controller configured to execute a secondary process. 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. A configuration management unit is also provided and 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. 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. The storage array is configured to service requests from one or more initiators.

[0012]In yet another embodiment, computer readable media is provided, having program instructions for operating a storage array for maintaining consistency in configuration data between processes running on an active controller and a standby controller of the storage array.

Problems solved by technology

Since the difference in access times between a cache memory and a hard drive are significant, the overall performance of the system is highly impacted by the cache hit ratio.

If initiators see storage arrays with excessive failures, even when a storage array is processing failover procedures, such storage arrays will be viewed as less than optimal.

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