Sandisk Technologies Inc.

Lsi Logic Corporation

Chayan Biswas

Akshay Mathur

Dharani Kotte

Sumant Kumar Patro

Baskaran Kannan

Paresh Chatterjee

Ragendra Mishra

Basavaraj Gurupadappa Hallyal

Senthil Thangaraj

Systems, methods and/or devices are used to enable real-time I/O pattern recognition to enhance performance and endurance of a storage device. In one aspect, the method includes (1) at a storage device, receiving from a host a plurality of input/output (I/O) requests, the I/O requests specifying operations to be performed in a plurality of regions in a logical address space of the host, and (2) performing one or more operations for each region of the plurality of regions in the logical address space of the host, including (a) maintaining a history of I/O request patterns in the region for a predetermined time period, and (b) using the history of I/O request patterns in the region to adjust subsequent I/O processing in the region.

Real-time I/O pattern recognition to enhance performance and endurance of a storage device

Systems, methods and/or devices are used to enable using history of I/O sizes and I/O sequences to trigger coalesced writes in a non-volatile storage device. In one aspect, the method includes (1) receiving a plurality of input/output (I/O) requests to be performed in a plurality of regions in a logical address space of a host, and (2) performing one or more operations for each region of the plurality of regions in the logical address space of the host, including (a) determining whether the region has a history of I/O requests to access data of size less than a predefined small-size threshold during a predetermined time period, (b) determining whether the region has a history of sequential write requests during the predetermined time period, and (c) if both determinations are true, coalescing subsequent write requests to the region.

Using history of I/O sizes and I/O sequences to trigger coalesced writes in a non-volatile storage device

Systems, methods and/or devices are used to enable using sub-region I/O history to cache repeatedly accessed sub-regions in a non-volatile storage device. In one aspect, the method includes (1) receiving a plurality of input/output (I/O) requests including read requests and write requests to be performed in a plurality of regions in a logical address space of a host, and (2) performing one or more operations for each region of the plurality of regions in the logical address space of the host, including, for each sub-region of a plurality of sub-regions of the region: (a) determining whether the sub-region is accessed more than a predetermined threshold number of times during a predetermined time period, and (b) if so, caching, from a storage medium of the storage device to a cache of the storage device, data from the sub-region.

Using sub-region I/O history to cache repeatedly accessed sub-regions in a non-volatile storage device

Systems, methods and/or devices are used to enable prioritizing garbage collection and block allocation based on I/O history for logical address regions. In one aspect, the method includes (1) receiving, at a storage device, a plurality of input/output (I/O) requests from a host, the plurality of I/O requests including read requests and write requests to be performed in a plurality of regions in a logical address space of the host, (2) in accordance with the plurality of I/O requests over a predetermined time period, identifying an idle region of the plurality of regions in the logical address space of the host, and (3) in accordance with the identification of the idle region, enabling garbage collection of data storage blocks, in the storage device, that store data in the idle region.

Prioritizing garbage collection and block allocation based on I/O history for logical address regions

Systems, methods and/or devices are used to enable identification of hot regions to enhance performance and endurance of a non-volatile storage device. In one aspect, the method includes (1) receiving a plurality of input/output (I/O) requests to be performed in a plurality of regions in a logical address space of a host, and (2) performing one or more operations for each region of the plurality of regions in the logical address space of the host, including (a) determining whether the region is accessed by the plurality of I/O requests more than a predetermined threshold number of times during a predetermined time period, (b) if so, marking the region with a hot region indicator, and (c) while the region is marked with the hot region indicator, identifying open blocks associated with the region, and marking each of the identified open blocks with a hot block indicator.

Identification of hot regions to enhance performance and endurance of a non-volatile storage device

Systems, methods and/or devices are used to enable using history of unaligned writes to cache data and avoid read-modify-writes in a non-volatile storage device. In one aspect, the method includes (1) receiving a plurality of input/output (I/O) requests including read requests and write requests to be performed in a plurality of regions in a logical address space of a host, and (2) performing one or more operations for each region of the plurality of regions in the logical address space of the host, including (a) determining whether the region has a history of unaligned write requests during a predetermined time period, and (b) if so: (i) determining one or more sub-regions within the region that are accessed more than a predetermined threshold number of times during the predetermined time period, and (ii) caching data from the determined one or more sub-regions.

Using history of unaligned writes to cache data and avoid read-modify-writes in a non-volatile storage device

Systems and methods for maintaining cache coherency between a first controller and a redundant peer controller while reducing communication overhead processing involved in the coherency message exchange. Header or meta-data information is accumulated in a buffer in a first controller along with updated cache data (if any) and forwarded to the peer controller. The accumulating information may be double buffered so that a buffer is filling as a previously filled buffer is transmitting to the peer controller. The peer controller processes the received information to update its mirror cache to maintain coherency with the first controller's cache memory with respect to dirty data. The method and systems avoid the need to update cache coherency in response to every flush operation performed within the first controller to thereby improve overall system performance.

Systems and methods for cache synchronization between redundant storage controllers

Methods and structure for initializing a RAID storage volume substantially in parallel with processing of host generated I/O requests. Initialization of a RAID volume may be performed as a background task in one aspect of the invention while host generated I/O requests proceed in parallel with the initialization. The initialization may preferably the performed by zeroing all data including parity for each stripe to thereby make each stripe XOR consistent. Host generated I/O requests to write information on the volume may utilize standard read-modify-write requests where the entire I/O request affects information in a portion of the volume already initialized by background processing. Other host I/O requests use standard techniques for generating parity for all stripes affected by the write requests. These and other features and aspects of the present invention make a newly defined RAID volume available for host processing is quickly as possible.

Methods and structure for rapid background initialization of a RAID logical unit

The present invention is directed to a system and method for increased data availability. In an aspect of the present invention, a method includes receiving a SMART indication from a data storage device included in a plurality of data storage devices configured as a RAID array. Data from the data storage device which originated the SMART indication is replicated to a second data storage device. The second data storage device was not originally configured in the RAID array with the plurality of data storage devices for data storage. The data storage device which originated the SMART indication from the RAID array is removed, thereby resulting the second data storage device and the plurality of data storage devices configured as a RAID array.

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Newark, CA, United States of America

Chayan Biswas