Patents by Inventor RAGHAVENDRA GOPALAKRISHNAN
RAGHAVENDRA GOPALAKRISHNAN has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 11934706Abstract: Aspects of a storage device provide an optimized data relocation scanning process which significantly reduces a number of page reads performed during a block relocation scan by consolidating logical addresses for multiple FMUs in a single FMU. The storage device includes a memory comprising a block including pages and FMUs, and a controller that is configured to store, in one of the FMUs, logical addresses for multiple FMUs. The controller is further configured, in response to a data relocation command, to read the logical addresses from the FMU, to determine at least one of the read logical addresses is mapped to a current FMU in a L2P mapping table, and to relocate data stored at the valid logical addresses in response to the determination. As a result, latency and power consumption associated with data relocation may be significantly reduced and storage device performance may thus be improved.Type: GrantFiled: December 22, 2021Date of Patent: March 19, 2024Assignee: WESTERN DIGITAL TECHNOLOGIES, INC.Inventors: Raghavendra Gopalakrishnan, Kalpit Bordia
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Patent number: 11853572Abstract: Aspects of the disclosure are directed to a storage device including a memory and a controller. The memory may include a plurality of flash memory blocks such as single level cell (SLC) blocks and multi-level cell (MLC) blocks. The controller may maintain a read count of each of the SLC blocks to determine which of the blocks contains data associated with the highest number of read commands. Based on the read commands, the controller may relocate the associated data into pages of MLC blocks that have a lower number of senses required to read the data stored in those blocks.Type: GrantFiled: May 5, 2022Date of Patent: December 26, 2023Assignee: WESTERN DIGITAL TECHNOLOGIES, INC.Inventors: Raghavendra Gopalakrishnan, Vivek Kumar
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Patent number: 11842062Abstract: The present disclosure generally relates to using irregular MetaBlocks (IRMBs) in both host and control pools. The IRMBs are used to ensure efficient wear leveling. Blocks in the control pool are swapped with blocks in the host pool upon exceeding a program-erase count (PEC) threshold. Additionally, the swapping algorithm for IRMBs can be used to ensure an efficient recovery from an ungraceful shutdown (UGSD) event.Type: GrantFiled: February 9, 2022Date of Patent: December 12, 2023Assignee: Western Digital Technologies, Inc.Inventors: Kalpit Bordia, Vinayak Bhat, Raghavendra Gopalakrishnan
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Publication number: 20230359378Abstract: Aspects of the disclosure are directed to a storage device including a memory and a controller. The memory may include a plurality of flash memory blocks such as single level cell (SLC) blocks and multi-level cell (MLC) blocks. The controller may maintain a read count of each of the SLC blocks to determine which of the blocks contains data associated with the highest number of read commands. Based on the read commands, the controller may relocate the associated data into pages of MLC blocks that have a lower number of senses required to read the data stored in those blocks.Type: ApplicationFiled: May 5, 2022Publication date: November 9, 2023Inventors: Raghavendra GOPALAKRISHNAN, Vivek KUMAR
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Publication number: 20230251788Abstract: The present disclosure generally relates to using irregular MetaBlocks (IRMBs) in both host and control pools. The IRMBs are used to ensure efficient wear leveling. Blocks in the control pool are swapped with blocks in the host pool upon exceeding a program-erase count (PEC) threshold. Additionally, the swapping algorithm for IRMBs can be used to ensure an efficient recovery from an ungraceful shutdown (UGSD) event.Type: ApplicationFiled: February 9, 2022Publication date: August 10, 2023Applicant: Western Digital Technologies, Inc.Inventors: Kalpit BORDIA, Vinayak BHAT, Raghavendra GOPALAKRISHNAN
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Publication number: 20230195389Abstract: Aspects of a storage device provide an optimized data relocation scanning process which significantly reduces a number of page reads performed during a block relocation scan by consolidating logical addresses for multiple FMUs in a single FMU. The storage device includes a memory comprising a block including pages and FMUs, and a controller that is configured to store, in one of the FMUs, logical addresses for multiple FMUs. The controller is further configured, in response to a data relocation command, to read the logical addresses from the FMU, to determine at least one of the read logical addresses is mapped to a current FMU in a L2P mapping table, and to relocate data stored at the valid logical addresses in response to the determination. As a result, latency and power consumption associated with data relocation may be significantly reduced and storage device performance may thus be improved.Type: ApplicationFiled: December 22, 2021Publication date: June 22, 2023Inventors: Raghavendra GOPALAKRISHNAN, Kalpit BORDIA
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Patent number: 11107518Abstract: A storage device having a wide range of operating temperatures is disclosed. Techniques disclosed herein may be used to operate MLC cells at higher temperatures before resorting to thermal throttling. Techniques disclosed herein may be used to operate MLC cells at lower temperatures without needing to pre-heat the storage device. SLC data stored in a first group of memory cells is folded to MLC data stored in a second group of memory cells while an operating temperature is outside a first temperature range. After the operating temperature is within a second temperature range, the data integrity of the MLC data is checked. The SLC data in the first group is folded to MLC data in a third group of memory cells responsive to the MLC data in the second group failing the data integrity check. The foregoing permits the storage device to increase its range in operating temperatures.Type: GrantFiled: June 25, 2020Date of Patent: August 31, 2021Assignee: Western Digital Technologies, Inc.Inventors: Raghavendra Gopalakrishnan, Joanna Lai, Dmitry Vaysman
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Patent number: 11062756Abstract: A storage device having a wide range of operating temperatures is disclosed. Techniques disclosed herein may be used to operate MLC cells at higher temperatures before resorting to thermal throttling. Techniques disclosed herein may be used to operate MLC cells at lower temperatures without needing to pre-heat the storage device. SLC data stored in a first group of memory cells is folded to MLC data stored in a second group of memory cells while an operating temperature is outside a first temperature range. After the operating temperature is within a second temperature range, the data integrity of the MLC data is checked. The SLC data in the first group is folded to MLC data in a third group of memory cells responsive to the MLC data in the second group failing the data integrity check. The foregoing permits the storage device to increase its range in operating temperatures.Type: GrantFiled: October 14, 2019Date of Patent: July 13, 2021Assignee: Western Digital Technologies, Inc.Inventors: Raghavendra Gopalakrishnan, Joanna Lai, Dmitry Vaysman
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Patent number: 11036582Abstract: An apparatus comprising non-volatile memory is configured to access a selected unit of encoded SLC data in the non-volatile memory during a first programming phase of a process of folding data stored at a single bit per memory cell to data stored at multiple bits per memory cell. The apparatus recovers the selected unit of SLC data based on redundancy data formed from units of SLC data that data include the selected unit of SLC data. The apparatus saves the recovered selected unit of SLC data to memory. The apparatus uses the saved recovered unit of SLC data during a second programming phase of folding the data stored at a single bit per memory cell to the data stored at multiple bits per memory cell, thereby saving considerable time in not having to again recover the SLC data using the redundancy data.Type: GrantFiled: September 27, 2019Date of Patent: June 15, 2021Assignee: Western Digital Technologies, Inc.Inventors: Raghavendra Gopalakrishnan, Bhanushankar Doni, Manohar Srinivasaiah
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Publication number: 20210132817Abstract: Aspects of a storage device are provided which allow transfer of data between cells at higher transfer rates based on a temperature of the cells. The storage device includes a memory having a plurality of first and second cells. Each of the second cells are configured to store more bits than each of the first cells. A controller is configured to store data in the first cells in response to a write command from a host device. The controller is further configured to transfer the data from the first cells to the second cells at a higher transfer rate when a temperature of the second cells is above a temperature threshold than when below the temperature threshold.Type: ApplicationFiled: October 31, 2019Publication date: May 6, 2021Inventors: Vinayak Bhat, Raghavendra Gopalakrishnan
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Publication number: 20210110865Abstract: A storage device having a wide range of operating temperatures is disclosed. Techniques disclosed herein may be used to operate MLC cells at higher temperatures before resorting to thermal throttling. Techniques disclosed herein may be used to operate MLC cells at lower temperatures without needing to pre-heat the storage device. SLC data stored in a first group of memory cells is folded to MLC data stored in a second group of memory cells while an operating temperature is outside a first temperature range. After the operating temperature is within a second temperature range, the data integrity of the MLC data is checked. The SLC data in the first group is folded to MLC data in a third group of memory cells responsive to the MLC data in the second group failing the data integrity check. The foregoing permits the storage device to increase its range in operating temperatures.Type: ApplicationFiled: October 14, 2019Publication date: April 15, 2021Applicant: Western Digital Technologies, Inc.Inventors: Raghavendra Gopalakrishnan, Joanna Lai, Dmitry Vaysman
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Publication number: 20210110866Abstract: A storage device having a wide range of operating temperatures is disclosed. Techniques disclosed herein may be used to operate MLC cells at higher temperatures before resorting to thermal throttling. Techniques disclosed herein may be used to operate MLC cells at lower temperatures without needing to pre-heat the storage device. SLC data stored in a first group of memory cells is folded to MLC data stored in a second group of memory cells while an operating temperature is outside a first temperature range. After the operating temperature is within a second temperature range, the data integrity of the MLC data is checked. The SLC data in the first group is folded to MLC data in a third group of memory cells responsive to the MLC data in the second group failing the data integrity check. The foregoing permits the storage device to increase its range in operating temperatures.Type: ApplicationFiled: June 25, 2020Publication date: April 15, 2021Applicant: Western Digital Technologies, Inc.Inventors: Raghavendra Gopalakrishnan, Joanna Lai, Dmitry Vaysman
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Publication number: 20210096948Abstract: An apparatus comprising non-volatile memory is configured to access a selected unit of encoded SLC data in the non-volatile memory during a first programming phase of a process of folding data stored at a single bit per memory cell to data stored at multiple bits per memory cell. The apparatus recovers the selected unit of SLC data based on redundancy data formed from units of SLC data that data include the selected unit of SLC data. The apparatus saves the recovered selected unit of SLC data to memory. The apparatus uses the saved recovered unit of SLC data during a second programming phase of folding the data stored at a single bit per memory cell to the data stored at multiple bits per memory cell, thereby saving considerable time in not having to again recover the SLC data using the redundancy data.Type: ApplicationFiled: September 27, 2019Publication date: April 1, 2021Applicant: Western Digital Technologies, Inc.Inventors: Raghavendra Gopalakrishnan, Bhanushankar Doni, Manohar Srinivasaiah
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Patent number: 10929285Abstract: A storage system and method are disclosed for generating a reverse map during a background operation and storing it in a host memory buffer. In one embodiment, a storage system is provided comprising a memory and a controller. The controller is configured to generate a physical-to-logical address map for at least part of the memory as a background operation and send the physical-to-logical address map to a host for storage in volatile memory in the host.Type: GrantFiled: February 27, 2018Date of Patent: February 23, 2021Assignee: Western Digital Technologies, Inc.Inventors: Raviraj R, Ritesh Tiwari, Raghavendra Gopalakrishnan
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Patent number: 10732877Abstract: In one embodiment, there is a method for managing data in a storage device comprising a non-volatile memory having a plurality of jumbo blocks, each jumbo block having a separate and distinct physical block address. The method comprises performing a folding operation data associated with a first virtual address from a plurality of Single Level Cell (SLC) jumbo blocks of the non-volatile memory to one Multilevel Cell (MLC) jumbo block of the non-volatile memory, receiving a read request to read data associated with a first logical block address, identifying that the first virtual address is associated with the first logical block address, determining whether a jumbo block associated with the first logical block address meets pre-SLC-overwrite criteria. In response to a determination that the jumbo block associated with the first logical block address meets pre-SLC-overwrite criteria, reading data from the SLC jumbo block associated with the first virtual address.Type: GrantFiled: March 25, 2019Date of Patent: August 4, 2020Assignee: WESTERN DIGITAL TECHNOLOGIES, INC.Inventors: Raghavendra Gopalakrishnan, Nicholas Thomas, Karin Inbar
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Patent number: 10635580Abstract: Apparatus, systems, methods, and computer program products for buffering storage device data in a host memory buffer (HMB) are presented. A non-volatile memory and a controller are in communication with a non-volatile memory. A controller is configured to receive an input/output (I/O) operation including data. A controller is configured to transmit at least a portion of data to an HMB of a host device separate from a non-volatile memory and a controller for storage until a trigger event occurs.Type: GrantFiled: July 9, 2018Date of Patent: April 28, 2020Assignee: Western Digital Technologies, Inc.Inventors: Kalpit Bordia, Raghavendra Gopalakrishnan, Sachin Krishna Kudva, Ashim Ranjan Saikia, Bhanushankar Doni Gurudath, Ramanathan Muthiah, Pradeep Sreedhar, Prashanth Reddy Enukonda, Ramkumar Ramamurthy
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Patent number: 10592141Abstract: Apparatuses, systems, and methods are disclosed for error characterization for control of non-volatile memory. An apparatus may include an array of non-volatile memory cells and a controller. A controller may be configured to acquire an error characterization for a region of memory. Also, an error characterization may comprise information about one or more types of errors to which a region of memory is susceptible. A controller may be configured to assign a region of memory into a logical group based on an error characterization. Further, a logical group may comprise a plurality of regions of memory. Additionally, a controller may be configured to service a write request by striping data across multiple regions assigned to a logical group.Type: GrantFiled: March 6, 2018Date of Patent: March 17, 2020Assignee: WESTERN DIGITAL TECHNOLOGIES, INC.Inventors: Vinay Vijendra Kumar Lakshmi, Raghavendra Gopalakrishnan
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Publication number: 20200012595Abstract: Apparatus, systems, methods, and computer program products for buffering storage device data in a host memory buffer (HMB) are presented. A non-volatile memory and a controller are in communication with a non-volatile memory. A controller is configured to receive an input/output (I/O) operation including data. A controller is configured to transmit at least a portion of data to an HMB of a host device separate from a non-volatile memory and a controller for storage until a trigger event occurs.Type: ApplicationFiled: July 9, 2018Publication date: January 9, 2020Applicant: Western Digital Technologies, Inc.Inventors: KALPIT BORDIA, RAGHAVENDRA GOPALAKRISHNAN, SACHIN KRISHNA KUDVA, ASHIM RANJAN SAIKIA, BHANUSHANKAR DONI GURUDATH, RAMANATHAN MUTHIAH, PRADEEP SREEDHAR, PRASHANTH REDDY ENUKONDA, RAMKUMAR RAMAMURTHY
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Patent number: 10496472Abstract: Apparatuses, systems, methods, and computer program products are disclosed for using a combined parity buffer memory for multiple open blocks of non-volatile memory. A controller is configured to accumulate, to a memory buffer, combined parity data for multiple open blocks of non-volatile memory in response to write operations to the multiple open blocks of non-volatile memory. A controller is configured to determine to close one block of multiple open blocks of non-volatile memory. A controller is configured to generate non-combined parity data for a block of non-volatile memory based on write operations to multiple open blocks of non-volatile memory.Type: GrantFiled: October 18, 2017Date of Patent: December 3, 2019Assignee: WESTERN DIGITAL TECHNOLOGIES, INC.Inventor: Raghavendra Gopalakrishnan
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Publication number: 20190278500Abstract: Apparatuses, systems, and methods are disclosed for error characterization for control of non-volatile memory. An apparatus may include an array of non-volatile memory cells and a controller. A controller may be configured to acquire an error characterization for a region of memory. Also, an error characterization may comprise information about one or more types of errors to which a region of memory is susceptible. A controller may be configured to assign a region of memory into a logical group based on an error characterization. Further, a logical group may comprise a plurality of regions of memory. Additionally, a controller may be configured to service a write request by striping data across multiple regions assigned to a logical group.Type: ApplicationFiled: March 6, 2018Publication date: September 12, 2019Applicant: Western Digital Technologies, Inc.Inventors: VINAY VIJENDRA KUMAR LAKSHMI, RAGHAVENDRA GOPALAKRISHNAN