Patents by Inventor Kroum Stoev

Kroum Stoev 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).

  • Publication number: 20240070017
    Abstract: Aspects of a storage device including a memory and a controller are provided. The controller may determine to perform garbage collection on a superblock. During the garbage collection process, the controller will typically move the superblock into an erase pool for erasing the superblock. However, aspects of the disclosure are directed to a method of measuring a raw bit error rate (RBER) of the superblock prior to erasure. The measured RBER may be used to estimate a data retention time of the storage device and provide the customer with an early warning notification if a health metric of the storage devices reaches a threshold retention time.
    Type: Application
    Filed: August 24, 2022
    Publication date: February 29, 2024
    Inventors: Lisha WANG, Jinyoung KIM, Andrew Yu-Jen WANG, Jinghuan CHEN, Kroum STOEV
  • Patent number: 10338841
    Abstract: Embodiments of the present disclosure generally relate to SSD management of non-volatile memory blocks for writing multiple data streams. The SSD may include a non-volatile memory organized into a number of superblocks. Each superblock includes a number of streamblocks. In one embodiment, a method of operating the SSD includes receiving a data stream, identifying an open superblock, identifying an available streamblock from the open superblock, and assigning the data stream to the available streamblock from the open streamblock. In another embodiment, a method of operating the SSD includes receiving a first data stream and a second data stream, writing the first data stream to the first streamblock and writing the second data stream to the second streamblock, and calculating a combined XOR parity information for the first streamblock and the second streamblock.
    Type: Grant
    Filed: June 27, 2017
    Date of Patent: July 2, 2019
    Assignee: WESTERN DIGITAL TECHNOLOGIES, INC.
    Inventors: Gulzar A. Kathawala, Liam Parker, Kroum Stoev
  • Patent number: 10223022
    Abstract: A set of superblocks can be constructed by a memory controller employing good blocks and partially bad blocks in a plurality of memory access units. Each functional memory access unit among the plurality of memory access units contributes a single block that is a good block or a partially bad block to each superblock. The memory controller can further construct a set of super word line zones within each superblock in the set of superblocks. Each block within a superblock contributes a good word line zone to each super word line zone. Upon encounter of a program error at run time, the super word line zones within the superblock may be modified to continue running the program employing modified super word line zones for the superblock.
    Type: Grant
    Filed: January 27, 2017
    Date of Patent: March 5, 2019
    Assignee: WESTERN DIGITAL TECHNOLOGIES, INC.
    Inventors: Meiman Lin Syu, Steven Sprouse, Kroum Stoev, Satish Vasudeva
  • Publication number: 20180373431
    Abstract: Embodiments of the present disclosure generally relate to SSD management of non-volatile memory blocks for writing multiple data streams. The SSD may include a non-volatile memory organized into a number of superblocks. Each superblock includes a number of streamblocks. In one embodiment, a method of operating the SSD includes receiving a data stream, identifying an open superblock, identifying an available streamblock from the open superblock, and assigning the data stream to the available streamblock from the open streamblock. In another embodiment, a method of operating the SSD includes receiving a first data stream and a second data stream, writing the first data stream to the first streamblock and writing the second data stream to the second streamblock, and calculating a combined XOR parity information for the first streamblock and the second streamblock.
    Type: Application
    Filed: June 27, 2017
    Publication date: December 27, 2018
    Inventors: Gulzar A. KATHAWALA, Liam PARKER, Kroum STOEV
  • Patent number: 10109352
    Abstract: Systems and methods for managing data retention in a solid-state storage system utilizing data retention flag bytes are disclosed. A data storage device includes a non-volatile memory comprising a plurality of non-volatile memory devices and a controller configured to write data to a memory unit of the non-volatile memory array and write a data retention flag value indicating a number of bits of the written data programmed in a first of a plurality of logical states. The controller is further configured to read the data and determine a number of bits having the first of the plurality of logical states in the read data, and determine a difference between the number of bits of the written data programmed in the first logical state and the number of bits having the first logical state in the read data. The difference is used to determine data retention characteristics of the non-volatile memory.
    Type: Grant
    Filed: April 10, 2017
    Date of Patent: October 23, 2018
    Assignee: Western Digital Technologies, Inc.
    Inventors: Dengtao Zhao, Yongke Sun, Haibo Li, Jui-Yao Yang, Kroum Stoev
  • Publication number: 20180217892
    Abstract: A set of superblocks can be constructed by a memory controller employing good blocks and partially bad blocks in a plurality of memory access units. Each functional memory access unit among the plurality of memory access units contributes a single block that is a good block or a partially bad block to each superblock. The memory controller can further construct a set of super word line zones within each superblock in the set of superblocks. Each block within a superblock contributes a good word line zone to each super word line zone. Upon encounter of a program error at run time, the super word line zones within the superblock may be modified to continue running the program employing modified super word line zones for the superblock.
    Type: Application
    Filed: January 27, 2017
    Publication date: August 2, 2018
    Inventors: Meiman Lin Syu, Steven Sprouse, Kroum Stoev, Satish Vasudeva
  • Publication number: 20170352423
    Abstract: Systems and methods for managing data retention in a solid-state storage system utilizing data retention flag bytes are disclosed. A data storage device includes a non-volatile memory comprising a plurality of non-volatile memory devices and a controller configured to write data to a memory unit of the non-volatile memory array and write a data retention flag value indicating a number of bits of the written data programmed in a first of a plurality of logical states. The controller is further configured to read the data and determine a number of bits having the first of the plurality of logical states in the read data, and determine a difference between the number of bits of the written data programmed in the first logical state and the number of bits having the first logical state in the read data. The difference is used to determine data retention characteristics of the non-volatile memory.
    Type: Application
    Filed: April 10, 2017
    Publication date: December 7, 2017
    Inventors: Dengtao Zhao, Yongke Sun, Haibo Li, Jui-Yao Yang, Kroum Stoev
  • Patent number: 9620220
    Abstract: Systems and methods for managing data retention in a solid-state storage system utilizing data retention flag bytes are disclosed. A data storage device includes a non-volatile memory comprising a plurality of non-volatile memory devices and a controller configured to write data to a memory unit of the non-volatile memory array and write a data retention flag value indicating a number of bits of the written data programmed in a first of a plurality of logical states. The controller is further configured to read the data and determine a number of bits having the first of the plurality of logical states in the read data, and determine a difference between the number of bits of the written data programmed in the first logical state and the number of bits having the first logical state in the read data. The difference is used to determine data retention characteristics of the non-volatile memory.
    Type: Grant
    Filed: February 12, 2016
    Date of Patent: April 11, 2017
    Assignee: Western Digital Technologies, Inc.
    Inventors: Dengtao Zhao, Yongke Sun, Haibo Li, Jui-Yao Yang, Kroum Stoev
  • Publication number: 20160163392
    Abstract: Systems and methods for managing data retention in a solid-state storage system utilizing data retention flag bytes are disclosed. A data storage device includes a non-volatile memory comprising a plurality of non-volatile memory devices and a controller configured to write data to a memory unit of the non-volatile memory array and write a data retention flag value indicating a number of bits of the written data programmed in a first of a plurality of logical states. The controller is further configured to read the data and determine a number of bits having the first of the plurality of logical states in the read data, and determine a difference between the number of bits of the written data programmed in the first logical state and the number of bits having the first logical state in the read data. The difference is used to determine data retention characteristics of the non-volatile memory.
    Type: Application
    Filed: February 12, 2016
    Publication date: June 9, 2016
    Inventors: Dengtao ZHAO, Yongke SUN, Haibo LI, Jui-Yao YANG, Kroum STOEV
  • Patent number: 9263136
    Abstract: Systems and methods for managing data retention in a solid-state storage system utilizing data retention flag bytes are disclosed. A data storage device includes a non-volatile memory comprising a plurality of non-volatile memory devices and a controller configured to write data to a memory unit of the non-volatile memory array and write a data retention flag value indicating a number of bits of the written data programmed in a first of a plurality of logical states. The controller is further configured to read the data and determine a number of bits having the first of the plurality of logical states in the read data, and determine a difference between the number of bits of the written data programmed in the first logical state and the number of bits having the first logical state in the read data. The difference is used to determine data retention characteristics of the non-volatile memory.
    Type: Grant
    Filed: November 26, 2013
    Date of Patent: February 16, 2016
    Assignee: Western Digital Technologies, Inc.
    Inventors: Dengtao Zhao, Yongke Sun, Haibo Li, Jui-Yao Yang, Kroum Stoev
  • Patent number: 7428124
    Abstract: A thin film magnetic head includes a slider body having a trailing surface meeting an air-bearing surface at a trailing edge. A magnetic read and write elements are disposed along the trailing surface near the trailing edge. The magnetic write element includes write poles and a coil. A portion of a heating element is disposed in a first general plane beneath the coil and above the magnetic read element. At least one thermally-insulating layer of material having a thermal conductivity of less than about 2.0 W/m-K extends in a second general plane substantially beneath the heating element.
    Type: Grant
    Filed: February 9, 2006
    Date of Patent: September 23, 2008
    Assignee: Western Digital (Fremont), LLC
    Inventors: Suping Song, Hai Jiang, Charles W. Miller, Kroum Stoev
  • Patent number: 7113366
    Abstract: A thin film electromagnetic head has an inductive transducer with a double-nosed ferromagnetic trailing pole layer. The trailing pole layer has a trailing pole tip disposed adjacent to a media-facing surface, a trailing pole yoke disposed distal to the media-facing surface, and a trailing pole nose disposed between the trailing pole tip and the trailing pole yoke. The media-facing surface extends as a substantially flat surface in all directions from the trailing pole tip. The length of the trailing pole nose may be at least twice as long as the trailing pole tip length. The width of the trailing pole nose can be 10 to 30 times as wide as the trailing pole tip width. An inductive transducer having a double-nosed trailing pole layer provides a higher ratio of on-track to off-track write fields, thereby improving the density with which data can be written to the recording media. Such a double-nosed trailing pole layer can be used in transducers for either longitudinal or perpendicular magnetic recording.
    Type: Grant
    Filed: November 7, 2002
    Date of Patent: September 26, 2006
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Yugang Wang, Kroum Stoev, Francis Liu, Yingjian Chen
  • Patent number: 6989972
    Abstract: Magnetoresistive (MR) sensors have leads that overlap a MR structure and distribute current to the MR structure so that the current is not concentrated in small portions of the leads. An electrically resistive capping layer can be formed between the leads and the MR structure to distribute the current. The leads can include resistive layers and conductive layers, the resistive layers having a thickness-to-resistivity ratio that is greater than that of each of the conductive layers. The resistive layers may protect the conductive layers during MR structure etching, so that the leads have broad layers of electrically conductive material for connection to MR structures. The broad leads conduct heat better than the read gap material that they replace, further reducing the temperature at the connection between the leads and the MR structure.
    Type: Grant
    Filed: September 30, 2002
    Date of Patent: January 24, 2006
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Kroum Stoev, Mathew Gibbons, Francis Liu, Bogdan M. Simion, Aparna C. Vadde, Jing Zhang, Yiming Huai, Marcos M. Lederman
  • Patent number: 6912106
    Abstract: A method and system for providing a recording head is disclosed. The method and system include providing a first pole, a second pole, a write gap and at least one coil. The write cap separates the first pole from the second pole. The coil(s) include a plurality of turns and is between the first and second poles. The first pole includes a pedestal that has a first portion and a second portion. The first portion includes a high moment electroplated material. The second portion includes a hot seed layer that has a high moment sputtered material. The second portion of the first pole is adjacent to the write gap.
    Type: Grant
    Filed: August 6, 2002
    Date of Patent: June 28, 2005
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Yingjian Chen, Qing He, Yugang Wang, Kroum Stoev, Francis Liu, Xiaozhong Dang
  • Patent number: 6906894
    Abstract: A read/write head and method of making the same are used in a data storage system, such as a disk drive, for perpendicular magnetic recording of data. The head employs a two-layer pole design with a main pole made of sputtered high moment magnetic material, and an adjunct pole made of electroplated soft magnetic film. The main pole is used to write data onto the medium, and is formed over the write coil. The adjunct pole is substantially recessed from the air bearing surface and is formed over the main pole. The present head design significantly enhances the magnetic write field, and substantially reduces side-writing that result in accidental erasure of data in adjacent tracks on the magnetic recording medium.
    Type: Grant
    Filed: July 29, 2004
    Date of Patent: June 14, 2005
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Yingjian Chen, Xiaozhong Dang, Francis H. Liu, Kroum Stoev, Hai Jiang, Yugang Wang, Xizeng Shi
  • Publication number: 20050007696
    Abstract: A read/write head and method of making the same are used in a data storage system, such as a disk drive, for perpendicular magnetic recording of data. The head employs a two-layer pole design with a main pole made of sputtered high moment magnetic material, and an adjunct pole made of electroplated soft magnetic film. The main pole is used to write data onto the medium, and is formed over the write coil. The adjunct pole is substantially recessed from the air bearing surface and is formed over the main pole. The present head design significantly enhances the magnetic write field, and substantially reduces side-writing that result in accidental erasure of data in adjacent tracks on the magnetic recording medium.
    Type: Application
    Filed: July 29, 2004
    Publication date: January 13, 2005
    Applicant: Western Digital (Fremont), Inc.
    Inventors: Yingjian Chen, Xiaozhong Dang, Francis Liu, Kroum Stoev, Hai Jiang, Yugang Wang, Xizeng Shi
  • Patent number: 6791793
    Abstract: A read/write head and method of making the same, are used in a data storage system, such as a disk drive, for perpendicular magnetic recording of data. The head employs a two-layer pole design with a main pole made of sputtered high moment magnetic material, and an adjunct pole made of electroplated soft magnetic film. The adjunct pole is substantially recessed from the air bearing surface. The present head design significantly enhances the magnetic write field, and substantially reduces side-writing that result in accidental erasure of data in adjacent tracks on the magnetic recording medium.
    Type: Grant
    Filed: September 14, 2001
    Date of Patent: September 14, 2004
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Yingjian Chen, Xiaozhong Dang, Francis H. Liu, Kroum Stoev, Hai Jiang, Yugang Wang, Xizeng Shi
  • Patent number: 6724572
    Abstract: In one aspect, an inductive transducer is disclosed having a leading pole layer and a leading pole tip, with the pole layer being further removed than the pole tip from a media-facing surface. In another aspect, an inductive transducer is disclosed having a magnetic pedestal disposed between a leading pole layer and a leading pole tip, with at least one of the pedestal and pole layer being further removed than the pole tip from a media-facing surface. In another aspect, a leading pole layer or pedestal may have a surface that slopes away from the media-facing surface with increasing distance forward from the leading pole tip.
    Type: Grant
    Filed: February 28, 2002
    Date of Patent: April 20, 2004
    Assignee: Western Digital, Inc.
    Inventors: Kroum Stoev, Yugang Wang, Francis Liu, Yingjian Chen, Xiaozhong Dang