Sandisk Technologies Inc.

Dharani Kotte

Akshay Mathur

Sumant Kumar Patro

Chayan Biswas

Baskaran Kannan

Satish Babu Vasudeva

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 using history of I/O sequences to trigger cached read ahead in a non-volatile storage device. 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, 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 sequential read requests during a predetermined time period, and (b) in accordance with a determination that the region has a history of sequential read requests during the predetermined time period, enabling read ahead logic for the region.

Using history of I/O sequences to trigger cached read ahead in a non-volatile storage device

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

In a memory system having non-volatile memory and volatile memory, write data are stored in a write-coalescing buffer in the volatile memory until the write data is written to non-volatile memory. First and second level address mapping tables are stored in the volatile memory and corresponding first and second level address mapping tables are stored in the non-volatile memory, and furthermore the second level address mapping table in the volatile memory contains entries corresponding to only a subset of the entries in the second level address mapping table in the non-volatile memory. The first address-mapping table in volatile memory includes entries storing pointers to entries in the second address-mapping table in volatile memory, entries storing pointers to locations in the write-coalescing buffer, and entries storing pointers to locations in the non-volatile memory that store data.

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Fremont, CA, United States of America

Dharani Kotte