Abstract: A method for managing data movement in a multi-level cache system includes selecting at least one outgoing data block from a primary cache when an unallocated space of the primary cache has reached a minimum threshold, initiating a de-stage process for de-staging the outgoing data block, and terminating the de-stage process when the unallocated space has reached an upper threshold. The de-stage process includes storing the outgoing data block in a secondary cache when a cache hit has occurred before. The cache hit may be an actual cache hit or a “ghost” cache hit wherein only metadata is stored in the secondary cache. A method for de-staging an outgoing data block from a higher level cache which includes storing an outgoing data block in a lower level cache when a cache hit rate satisfies a predetermined condition and storing metadata in the lower level cache is also disclosed.

Abstract: Methods and structure for reprogramming firmware in a storage controller using a virtual machine management (VMM) environment. A storage process (current firmware) in the storage controller operates in a current virtual machine (VM) under control of a hypervisor. Reprogrammed (new) firmware is loaded into a new virtual machine under control of the hypervisor. The new firmware initializes and directs the current firmware to quiesce its processing. The new firmware also requests the hypervisor to map data in the memory space of the current virtual machine into the memory space of the new virtual machine and to transfer ownership/control of devices and network addresses from the current virtual machine to the new virtual machine. The new firmware operating on the new virtual machine then takes control of the storage controller and resumes processing of requests.

Abstract: Methods and structure for automated determination and reconfiguration of the size of a cache memory in a storage system. Features and aspects hereof generate historical information regarding frequency of hits on cache lines in the cache memory. The history maintained is then analyzed to determine a desired cache memory size. The historical information regarding cache memory usage may be communicated to a user who may then direct the storage system to reconfigure its cache memory to a desired cache memory size. In other embodiments, the storage system may automatically determine the desired cache memory size and reconfigure its cache memory. The method may be performed automatically periodically, and/or in response to a user's request, and/or in response to detecting thrashing caused by least recently used (LRU) cache replacement algorithms in the storage system.

Abstract: Methods and structure for automated determination and reconfiguration of the size of a cache memory in a storage system. Features and aspects hereof generate historical information regarding frequency of hits on cache lines in the cache memory. The history maintained is then analyzed to determine a desired cache memory size. The historical information regarding cache memory usage may be communicated to a user who may then direct the storage system to reconfigure its cache memory to a desired cache memory size. In other embodiments, the storage system may automatically determine the desired cache memory size and reconfigure its cache memory. The method may be performed automatically periodically, and/or in response to a user's request, and/or in response to detecting thrashing caused by least recently used (LRU) cache replacement algorithms in the storage system.

Abstract: Methods and structure for reprogramming firmware in a storage controller using a virtual machine management (VMM) environment. A storage process (current firmware) in the storage controller operates in a current virtual machine (VM) under control of a hypervisor. Reprogrammed (new) firmware is loaded into a new virtual machine under control of the hypervisor. The new firmware initializes and directs the current firmware to quiesce its processing. The new firmware also requests the hypervisor to map data in the memory space of the current virtual machine into the memory space of the new virtual machine and to transfer ownership/control of devices and network addresses from the current virtual machine to the new virtual machine. The new firmware operating on the new virtual machine then takes control of the storage controller and resumes processing of requests.

Abstract: A method for managing data movement in a multi-level cache system having a primary cache and a secondary cache. The method includes determining whether an unallocated space of the primary cache has reached a minimum threshold; selecting at least one outgoing data block from the primary cache when the primary cache reached the minimum threshold; initiating a de-stage process for de-staging the outgoing data block from the primary cache; and terminating the de-stage process when the unallocated space of the primary cache has reached an upper threshold. The de-stage process further includes determining whether a cache hit has occurred in the secondary cache before; storing the outgoing data block in the secondary cache when the cache hit has occurred in the secondary cache before; generating and storing metadata regarding the outgoing data block; and deleting the outgoing data block from the primary cache.

Abstract: A method for detection of hot-swap of disk drives in a storage subsystem devoid of special circuits for such detection and for buffering of bus signals. Typical prior designs utilize special circuits such as disk drive canisters for physically and electronically connecting the disk drives to the storage subsystem. These canisters provided electronic buffering to reduce or eliminate transient (noise and glitch) signals associated with hot-swap drive removal and insertion. In addition, such canisters provided special purpose circuits to inform storage subsystem control modules that a possible insertion or removal occurred by forcing a reset of the interconnection bus in response to detection of such transient signals. The present invention provides for such detection without need for such complex (e.g., costly) special purpose circuits.

Abstract: Methods and associated apparatus for automatically synchronizing the operating code between a plurality of controllers. In a first embodiment after the spare controller is swapped into the storage subsystem, if the native controller determines that the spare controller's operating code is incompatible with the native controller's operating code, then the native controller notifies the spare controller that synchronization is required between both controllers. The native controller creates an image of its operating code including configuration parameters, and copies this "synch info" into a reserved area of cache memory. The spare controller's main CPU utilizes mirroring routines to copy the operating code and configuration parameters into a reserved area of its cache memory. After the transfer is complete, the spare controller's main CPU loads the operating code and configuration parameters into its program memory and resets itself to operate with the modified program memory.