Avago Technologies International Sales Pte. Limited

Avago Technologies General IP (Singapore) Pte. Ltd.

Panthini Pandit

Horia Cristian Simionescu

Timothy E Hoglund

Gowrisankar Radhakrishnan

Sridhar Rao Veerla

A system and method for efficient cache flushing are provided. The disclosed method includes maintaining a data structure in connection with a plurality of blocks used for data caching, the data structure including a row lock wait list section. The method further includes receiving an Input/Output (I/O) request, performing a hash search for the I/O request against the data structure, and based on the results of the hash search, locking at least one row in a data cache thereby preventing read and write operations from being performed on the at least one row until the at least one row is unlocked.

Method and system for hardware accelerated row lock for a write back volume

A system and method for managing bad blocks in a hardware accelerated caching solution are provided. The disclosed method includes receiving an Input/Output (I/O) request, performing a hash search for the I/O request against a hash slot data structure, and based on the results of the hash search, either performing the I/O request with a data block identified in the I/O request or diverting the I/O request to a new data block not identified in the I/O request. The diversion may also include diverting the I/O request from hardware to firmware of a memory controller.

Method and system for handling bad blocks in a hardware accelerated caching solution

A system and method for performing a copyback operation are provided. The disclosed method includes initiating a copyback process to move data from an online data storage drive to a spare data storage drive by setting an indicator in hardware to divert all write completions on the online data storage drive. The method further includes, while the indicator in hardware is set to divert the write completions, incrementing on a per-strip basis a copy of data from the online data storage drive to the spare data storage drive. The method further includes only after all data from the online data storage drive has been copied to the spare data storage drive, changing the setting of the indicator in hardware so that write requests received for the online data storage drive during the copyback process are re-issued on to the spare data storage drive.

Method and system for hardware accelerated copyback

A system and method for efficient cache flushing are provided. The disclosed method includes allocating one or more Internal Scatter Gather Lists (ISGLs) for the cache flush, populating the one or more ISGLs with Cache Segment Identifiers (CSIDs) and corresponding Buffer Segment Identifiers (BSIDs) of each strip that is identified as dirty, of a skip-type Internal Scatter Gather Element (ISGE), or of a missing arm-type ISGE. The disclosed method further includes allocating a flush Local Message Identifier (LMID) as a message to be used in connection with processing the cache flush, populating the flush LMID with an identifier of the one or more ISGLs, and transferring the flush LMID to a cache manager module to enable the cache manager module to execute the cache flush based on information contained in the flush LMID.

Method and system for hardware accelerated cache flush

A system and method for efficient cache buffering are provided. The disclosed method determining that a read-ahead operation is to be performed in response to receiving a host Input/Output (I/O) command. In response to determining that the read-ahead operation is to be performed, allocating a new Local Message Identifier (LMID) for the read-ahead operation. The method further includes sending a buffer allocation request to a buffer manager module, the buffer allocation request containing parameters associated with the read-ahead operation and then causing the buffer manager module to allocate at least one Internal Scatter Gather List (ISGL) and Buffer Section Identifier (BSID) in accordance with the parameters contained in the buffer allocation request. The method further includes enabling the cache manager module to perform a hash search using a row or strip number and identification information available in the new LMID.

Method and system for hardware accelerated read-ahead caching

A system and method for efficient cache buffering are provided. The disclosed method includes receiving an Input/Output (I/O) command from a host system at a storage controller, parsing the I/O command at the storage controller with a host I/O manager to extract command instructions therefrom. The host I/O manager is able to generate at least one local message that includes the command instructions extracted from the I/O command and transmit the at least one local message to a cache manager. The cache manager is enabled to work in local memory to execute the command instructions contained in the at least one message. The cache manager is also configured to chain multiple buffer segments together on-demand to support multiple stripe sizes that are specific to the I/O command received from the host system.

Method and system for efficient cache buffering supporting variable stripe sizes to enable hardware acceleration

A system and method for efficient cache buffering are provided. The disclosed method includes receiving a host command from a host, extracting command information from the host command, determining an Input/Output (I/O) action to be taken in connection with the host command, determining that the I/O action spans more than one strip, and based on the I/O action spanning more than one strip, allocating a cache frame anchor for a row on-demand along with a cache frame anchor for a strip to accommodate the I/O action.

Method and system for efficient cache buffering in a system having parity arms to enable hardware acceleration

A system and method for efficient cache buffering are provided. The disclosed method includes receiving a host command from a host, extracting command information from the host command, determining an Input/Output (I/O) action to be taken in connection with the host command, identifying a particular memory module from among a plurality of memory modules to execute the I/O action, generating an accelerated I/O message for transmission to the particular memory module, the accelerated I/O message comprising at least one Internal Scatter Gather List (ISGL) having a plurality of Scatter Gather Extents (SGEs) that enable the particular memory module to execute the I/O action solely based on the at least one ISGL, and transmitting the accelerated I/O message to the particular memory module.

Memory controller utilizing scatter gather list techniques

Methods and structure for formatting and processing Scatter Gather Lists (SGLs). One exemplary embodiment is a storage controller that includes a cache memory storing data for a logical volume, and a control unit. The control unit is able to service an Input/Output (I/O) request based on a Scatter Gather List (SGL) that refers to the cache memory, the SGL comprising multiple entries that each include a flag field and an identifier (ID) field. The entries are assigned to categories that are each associated with a different set of stored processing instructions. The control unit is able to identify a category for an entry based on a combination of both flag field and ID field for the entry, and the control unit is able to process the entry using the set of instructions associated with the identified category.

Space efficient formats for scatter gather lists

Methods and structure for managing cache memory for a storage controller. One exemplary embodiment a Redundant Array of Independent Disks (RAID) storage controller. The storage controller includes an interface operable to receive Input/Output (I/O) requests from a host, a Direct Memory Access (DMA) module, a memory comprising cache data for a logical volume, and a control unit. The control unit is able to generate Scatter Gather Lists (SGLs) that indicate the location of cache data for incoming read requests. Each SGL is stored in the memory, and at least one SGL points to cache data that is no longer indexed by the cache. The control unit is also able to service an incoming read request based on the SGL, by directing the DMA module to transfer the cache data that is no longer indexed to the host.

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Bengaluru, India

Panthini Pandit