Distributing Metadata Across Multiple Different Disruption Regions Within an Asymmetric Memory System

• US 20090157989A1
• Filed: 12/15/2008
• Published: 06/18/2009
• Est. Priority Date: 12/14/2007
• Status: Active Grant

• Current Assignee: Sandisk Technologies Incorporated (Western Digital Corporation)
• Original Assignee: Virident Systems Inc. (Western Digital Corporation)
• Inventors: Karamcheti, Vijay, Singhai, Ashish
• Granted Patent: US 9,727,452 B2
• Time in Patent Office: Days
• US Class Current: 711/156
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/1032 Reliability improvement, data loss prevention, degraded operation etc
• CPC Class Codes: G06F 2212/7207 management of metadata or control data
• CPC Class Codes: G06F 2212/7208 Multiple device management, e.g. distributing data over multiple flash devices

Abstract

Metadata that corresponds to application data is distributed across different disruption regions of an asymmetric memory component such that metadata is written in the same disruption region as the application data to which it corresponds. A first block of application data is written to a first disruption region and a second block of application data is written to a second disruption region. A first block of metadata corresponding to the first block of application data and a second block of metadata corresponding to the second block of application data both are generated. The first block of metadata is written to the first disruption region and the second block of metadata is written to the second disruption region such that the first and second blocks of metadata are written to the same disruption regions as the blocks of application data to which they correspond.

Claims

1. A method of distributing metadata that corresponds to application data for a file system across multiple different disruption regions of an asymmetric memory component such that metadata is written in the same disruption region of the asymmetric memory component as the application data to which the metadata corresponds, where individual disruption regions of the asymmetric memory component include physical blocks and are configured such that writing to a disruption region of the asymmetric memory component affects the availability of other physical blocks within the same disruption region of the asymmetric memory component, the method comprising:

writing a first block of application data to a first disruption region of the asymmetric memory component and writing a second block of application data that is different than the first block of application data to a second disruption region of the asymmetric memory component that is different than the first disruption region of the asymmetric memory component, the first and second blocks of application data corresponding to first and second logical blocks of the file system respectively;

generating a first block of metadata that corresponds to the first block of application data and that identifies the first block of application data as corresponding to the first logical block of the file system and generating a second block of metadata that corresponds to the second block of application data and that identifies the second block of application data as corresponding to the second logical block of the file system; and

writing the first block of metadata to the first disruption region of the asymmetric memory component and writing the second block of metadata to the second disruption region of the asymmetric memory component such that the first and second blocks of metadata are written to the same disruption regions of the asymmetric memory component as the blocks of application data to which they correspond.

2. A method of writing application data to a memory storage system that includes an asymmetric memory component having multiple disruption regions such that metadata related to a write operation performed to write application data to an individual disruption region of the asymmetric memory component is written to the same individual disruption region of the asymmetric memory component as the application data, where individual disruption regions of the asymmetric memory component include one or more physical blocks, and where individual disruption regions of the asymmetric memory component are configured such that writing to a physical block within a disruption region of the asymmetric memory component affects the availability of other physical blocks within the same disruption region of the asymmetric memory component, the method comprising:

processing an instruction to write a first quantum of application data to the asymmetric memory component;

in response to processing the instruction to write the first quantum of application data to the asymmetric memory component, performing a first write operation that includes;

generating metadata related to the first write operation, and

writing the first quantum of application data and the metadata related to the first write operation to different physical blocks within a first disruption region of the asymmetric memory component such that the first quantum of application data and the metadata related to the first write operation both are written to the same disruption region of the asymmetric memory component;

processing an instruction to write a second quantum of application data to the asymmetric memory component;

in response to processing the instruction to write the second quantum of application data to the asymmetric memory component, performing a second write operation that includes;

generating metadata related to the second write operation, and

writing the second quantum of application data and the metadata related to the second write operation to different physical blocks within a second disruption region of the asymmetric memory component that is different from the first disruption region of the asymmetric memory component, such that the second quantum of application data and the metadata related to the second write operation both are written to the same disruption region of the asymmetric memory component.

3. The method of claim 2 wherein:

generating metadata related to the first write operation includes determining that the first write operation includes writing the first quantum of application data to a particular physical block within the first disruption region of the asymmetric memory component; and

writing the metadata related to the first write operation includes writing, to a different physical block within the first disruption region of the asymmetric memory component, metadata that identifies the particular physical block within the first disruption region of the asymmetric memory component as storing the first quantum of application data.

4. The method of claim 3 wherein:

generating the metadata related to the first write operation further includes determining a relative time at which the first write operation occurs; and

writing the metadata related to the first write operation includes writing, to the different physical block within the first disruption region of the asymmetric memory component, metadata that specifies the relative time at which the first write operation was determined to occur.

5. The method of claim 4 wherein:

determining a relative time at which the first write operation occurs includes determining a physical date and time at which the first write operation occurs; and

writing the metadata related to the first write operation includes writing, to the different physical block within the first disruption region of the asymmetric memory component, metadata that specifies the physical date and time at which the first write operation was determined to occur.

6. The method of claim 3 wherein:

generating metadata related to the first write operation further includes determining a number of times that the particular physical block within the first disruption region of the asymmetric memory component has been erased; and

writing the metadata related to the first write operation includes writing, to the different physical block within the first disruption region of the asymmetric memory component, metadata that specifies the number of times that the particular physical block within the first disruption region of the asymmetric memory component has been erased.

7. The method of claim 3 wherein:

processing an instruction to write a first quantum of application data to the asymmetric memory component includes;

receiving an instruction to write the first quantum of application data to a logical volume, the instruction specifying a particular logical block within the logical volume to which the first quantum of application data is to be written, and

converting the instruction to write the first quantum of application data to the particular logical block within the logical volume into an instruction to write the first quantum of application data to the particular physical block within the first disruption region of the asymmetric memory component;

generating metadata related to the first write operation includes determining to which logical block within which logical volume the received instruction specified that the first quantum of application data was to be written; and

writing the metadata related to the first write operation includes writing, to the different physical block within the first disruption region of the asymmetric memory component, metadata that;

identifies the particular physical block within the first disruption region of the asymmetric memory component as corresponding to the particular logical block of the logical volume, and

identifies the particular physical block within the first disruption region of the asymmetric memory component as actually storing the first quantum of application data that the received instruction specified was to be written to the particular logical block within the logical volume.

8. The method of claim 7 wherein:

the logical volume is associated with a volume identifier;

the particular logical block within the logical volume is associated with a volume offset that identifies the particular logical block'"'"'s offset within the logical volume;

receiving an instruction to write the first quantum of application data to a particular logical block within a logical volume includes receiving an instruction that specifies that the first quantum of application data is to be written to the particular logical block within the logical volume by specifying the volume identifier of the logical volume and the volume offset of the particular logical block; and

writing the metadata related to the first write operation includes writing, to the different physical block within the first disruption region of the asymmetric memory component, the volume identifier and the volume offset.

9. The method of claim 7 wherein:

the memory storage system includes a volatile memory component that is different from the asymmetric memory component; and

the method further comprises;

maintaining, in the volatile memory component, a volume information table that maps logical blocks within the volume to corresponding physical blocks that store application data associated with the individual logical blocks to which they correspond, the physical blocks being located within disruption regions of the asymmetric memory component; and

updating the volume information table to identify the particular physical block within the first disruption region of the asymmetric memory component as corresponding to the particular logical block within the logical volume and to identify the particular physical block within the first disruption region of the asymmetric memory component as storing the first quantum of application data that the received instruction specified was to be written to the particular logical block within the logical volume.

10. The method of claim 9 wherein:

processing an instruction to write a second quantum of application data to the asymmetric memory component includes;

receiving an instruction to write the second quantum of application data to the logical volume, the instruction specifying an individual logical block within the logical volume to which the second quantum of application data is to be written, and

converting the instruction to write the second quantum of application data to the individual logical block within the logical volume into an instruction to write the second quantum of application data to a particular physical block within the second disruption region of the asymmetric memory component;

generating metadata related to the second write operation includes;

determining that the received instruction specified that the second quantum of application data was to be written to the individual logical block within the logical volume, and

determining that the second write operation includes writing the second quantum of application data to a particular physical block within the second disruption region of the asymmetric memory component,

writing the metadata related to the second write operation includes writing, to a different physical block within the second disruption region of the asymmetric memory component, metadata that;

identifies the particular physical block within the second disruption region of the asymmetric memory component as corresponding to the individual logical block of the logical volume, and

identifies the particular physical block within the second disruption region of the asymmetric memory component as actually storing the second quantum of application data that the received instruction specified was to be written to the individual logical block within the logical volume; and

the method further comprises;

updating the volume information table to identify the particular physical block within the second disruption region of the asymmetric memory component as corresponding to the individual logical block within the logical volume and to identify the particular physical block within the second disruption region of the asymmetric memory component as storing the second quantum of application data that the received instruction specified was to be written to the individual logical block within the logical volume,

determining that the volume information table needs to be recreated, and

in response to determining that the volume information table needs to be recreated, recreating the volume information table by;

accessing metadata stored in at least two different disruption regions of the asymmetric memory component, including;

accessing, from the different physical block within the first disruption region of the asymmetric memory component, the metadata that identifies the particular physical block within the first disruption region of the asymmetric memory component as corresponding to the particular logical block of the logical volume and identifies the particular physical block within the first disruption region of the asymmetric memory component as actually storing the first quantum of application data, and

accessing, from the different physical block within the second disruption region of the asymmetric memory component, the metadata that identifies the particular physical block within the second disruption region of the asymmetric memory component as corresponding to the individual logical block of the logical volume and identifies the particular physical block within the second disruption region of the asymmetric memory component as actually storing the second quantum of application data,

based on accessing the metadata stored in the at least two different disruption regions of the asymmetric memory component identifying physical blocks within the different disruption regions of the asymmetric memory component that correspond to logical blocks of the logical volume and that store application data associated with their corresponding logical blocks, including;

determining that the particular physical block within the first disruption region of the asymmetric memory component corresponds to the particular logical block of the logical volume and actually stores the first quantum of application data,

determining that the particular physical block within the second disruption region of the asymmetric memory component corresponds to the individual logical block of the logical volume and actually stores the second quantum of application data,

determining, for at least one other logical block of the logical volume, that a specific physical block within the asymmetric memory component that the accessed metadata identifies as corresponding to the other logical block and storing a third quantum of application data associated with the other logical block was written to more recently than at least one other physical block within the asymmetric memory component that the accessed metadata identifies as corresponding to the other logical block and storing a third quantum of application data associated with the other logical block, and

based on having identified physical blocks within the different disruption regions of the asymmetric memory component that correspond to logical blocks of the logical volume and that store application data associated with their corresponding logical blocks, configuring the recreated volume information table to map logical blocks within the logical volume to the corresponding physical blocks that store application data associated with the logical blocks to which they correspond, including;

configuring the recreated volume information table to map the particular physical block within the first disruption region of the asymmetric memory component to the particular logical block within the logical volume based on having determined that the particular physical block within the first disruption region of the asymmetric memory component corresponds to the particular logical block of the logical volume and actually stores the first quantum of application data,

configuring the recreated volume information table to map the particular physical block within the second disruption region of the asymmetric memory component to the individual logical block within the logical volume based on having determined that the particular physical block within the second disruption region of the asymmetric memory component corresponds to the individual logical block of the logical volume and actually stores the second quantum of application data, and

configuring the recreated volume information table to map the specific physical block within the asymmetric memory component to the other logical block within the logical volume based on having determined that the specific physical block was written to more recently than at least one other physical block within the asymmetric memory component that the accessed metadata identifies as corresponding to the other logical block and storing the third quantum of application data associated with the other logical block.

11. The method of claim 7 further comprising:

before processing the first instruction to write the first quantum of application data to the asymmetric memory component;

receiving an instruction to create the logical volume, the instruction to create the logical volume specifying a name for the logical volume and a number of logical blocks to be included within the logical volume; and

in response to receiving the instruction to create the logical volume;

creating the logical volume,

creating a volume metadata structure, and

configuring the volume metadata structure including;

writing the name for the logical volume to the volume metadata structure,

writing the number of logical blocks included within the logical volume to the volume metadata structure,

determining a relative time at which the logical volume is created, and

writing the determined relative time at which the logical volume was created to the volume metadata structure.

12. The method of claim 11 further comprising:

receiving an instruction to extend the logical volume to include an additional number of logical blocks; and

in response to receiving the instruction to extend the logical volume to include the additional number of logical blocks;

extending the logical volume to include the additional number of logical blocks, and

updating the volume metadata structure to reflect that the logical volume has been extended to include the additional number of logical blocks.

13. The method of claim 2 further comprising reserving one or more physical blocks within the first disruption region of the asymmetric memory component exclusively for storing metadata related to other physical blocks within the first disruption region of the asymmetric memory component, wherein writing the metadata related to the first write operation includes writing the metadata related to the first write operation to one of the one or more physical blocks within the first disruption region of the asymmetric memory component that are reserved exclusively for storing metadata related to other physical blocks within the first disruption region of the asymmetric memory component.

14. The method of claim 13 wherein:

reserving one or more physical blocks within the first disruption region of the asymmetric memory component exclusively for storing metadata related to other physical blocks within the first disruption region of the asymmetric memory component includes reserving a first physical block and a second physical block within the first disruption region of the asymmetric memory component exclusively for storing metadata related to other physical blocks within the first disruption region of the asymmetric memory component; and

writing the metadata related to the first write operation to one of the one or more physical blocks within the first disruption region of the asymmetric memory component that are reserved exclusively for storing metadata related to other physical blocks within the first disruption region of the asymmetric memory component includes;

determining that metadata stored in the first physical block reserved exclusively for storing metadata reflects a present state of the first disruption region and that the second physical block reserved exclusively for storing metadata is available to be written to,

copying metadata stored in the first physical block reserved exclusively for storing metadata,

updating the metadata copied from the first physical block reserved exclusively for storing metadata to include the metadata related to the first write operation, and

writing the updated metadata to the second physical block reserved exclusively for storing metadata.

15. The method of claim 13 further comprising maintaining a log in the one or more physical blocks within the first disruption region of the asymmetric memory component that are reserved exclusively for storing metadata related to other physical blocks within the first disruption region of the asymmetric memory component, the log including metadata entries related to previous write operations that have been performed on other physical blocks within the first disruption region of the asymmetric memory component, wherein writing the metadata related to the first write operation includes adding, to the log, a new metadata entry related to the first write operation.

16. The method of claim 15 wherein:

generating metadata related to the first write operation includes determining that performing the first write operation includes writing the first quantum of application data to a particular physical block within the first disruption region of the asymmetric memory component; and

adding, to the log, a new metadata entry related to the first write operation includes adding, to the log, a new metadata entry related to the first write operation that identifies the particular physical block within the first disruption region of the asymmetric memory component as storing the first quantum of application data.

17. The method of claim 15 wherein:

processing an instruction to write a first quantum of application data to the asymmetric memory component includes;

receiving an instruction to write the first quantum of application data to a logical volume, the instruction specifying a logical block within the logical volume to which the first quantum of application data is to be written, and

converting the instruction to write the first quantum of application data to the logical block within the logical volume into an instruction to write the first quantum of application data to the particular physical block within the first disruption region of the asymmetric memory component;

generating metadata related to the first write operation includes determining to which logical block within which logical volume the received instruction specified that the first quantum of application data was to be written; and

adding, to the log, a new metadata entry related to the first write operation includes adding, to the log, a new metadata entry related to the first write operation that;

identifies the particular physical block within the first disruption region of the asymmetric memory component as corresponding to the logical block of the logical volume, and

identifies the particular physical block within the first disruption region of the asymmetric memory component as actually storing the first quantum of application data that the received instruction specified was to be written to the logical block within the logical volume.

18. The method of claim 17 wherein:

generating metadata related to the first write operation further includes;

determining a relative time at which the first write operation occurs, and

determining a number of times that the particular physical block within the first disruption region of the asymmetric memory component has been erased; and

adding, to the log, a new metadata entry related to the first write operation includes adding, to the log, a new metadata entry related to the first write operation that specifies;

the relative time at which the first write operation was determined to occur, and

the number of times that the particular physical block within the first disruption region of the asymmetric memory component has been erased.

19. The method of claim 15 wherein:

reserving one or more physical blocks within the first disruption region of the asymmetric memory component exclusively for storing metadata related to other physical blocks within the first disruption region of the asymmetric memory component includes reserving a first physical block and a second physical block within the first disruption region of the asymmetric memory component exclusively for storing metadata related to other physical blocks within the first disruption region of the asymmetric memory component;

maintaining a log in the one or more physical blocks within the first disruption region of the asymmetric memory component that are reserved exclusively for storing metadata related to other physical blocks within the first disruption region includes maintaining a log in the first physical block reserved exclusively for storing metadata; and

the method further comprises;

detecting that a current size of the log maintained in the first physical block reserved exclusively for storing metadata exceeds a predetermined threshold value,

in response to detecting that the current size of the log maintained in the first physical block reserved exclusively for storing metadata exceeds a predetermined threshold value;

copying the log maintained in the first physical block reserved exclusively for storing metadata,

collapsing the copied log by removing one or more outdated entries from the copied log,

writing the collapsed log to the second physical block reserved exclusively for storing metadata, and

erasing the first physical block reserved exclusively for storing metadata.

20. The method of claim 2 wherein:

the instruction to write a first quantum of application data to the asymmetric memory component is an instruction to update a first quantum of application data stored in a sector of a particular physical block within the first disruption region of the asymmetric memory component, and

writing the first quantum of application data includes writing the updated first quantum of application data to the sector of the particular physical block.

21. The method of claim 2 wherein:

the instruction to write a first quantum of application data to the asymmetric memory component is an instruction to update a first quantum of application data stored in a sector of a particular physical block within the first disruption region of the asymmetric memory component, and

writing the first quantum of application data includes;

copying application data from other sectors of the particular physical block to another physical block, and

writing the updated first quantum of application data to a sector of the other particular block.

22. The method of claim 2 wherein the first disruption region of the asymmetric memory component is a first bank of the asymmetric memory unit and the second disruption region of the asymmetric memory component is a second bank of the asymmetric memory unit that is different from the first bank of the asymmetric memory unit such that:

writing the first quantum of application data and the metadata related to the first write operation to different physical blocks within the first disruption region of the asymmetric memory component includes writing the first quantum of application data and the metadata related to the first write operation to different physical blocks within the first bank of the asymmetric memory component such that the first quantum of application data and the metadata related to the first write operation both are written to the same bank of the asymmetric memory component; and

writing the second quantum of application data and the metadata related to the second write operation to different physical blocks within the second disruption region of the asymmetric memory component includes writing the second quantum of application data and the metadata related to the second write operation to different physical blocks within the second bank of the asymmetric memory component such that the second quantum of application data and the metadata related to the second write operation both are written to the same bank of the asymmetric memory component.

24. The memory storage system of claim 22 wherein:

the first physical metadata block is configured to maintain a first log for storing a first set of metadata entries that are related to write operations performed on individual physical data blocks of the first set of physical data blocks within the first disruption region of asymmetric memory and that identify individual physical data blocks of the first set of physical data blocks within the first disruption region of asymmetric memory as corresponding to individual logical blocks and storing application data associated with the individual logical blocks to which the individual physical data blocks of the first set of physical data blocks within the first disruption region of asymmetric memory are identified as corresponding; and

the third physical metadata block is configured to maintain a second log for storing a second set of metadata entries that are related to write operations performed on individual physical data blocks of the second set of physical data blocks within the second disruption region of asymmetric memory and that identify individual physical data blocks of the second set of physical data blocks within the second disruption region of asymmetric memory as corresponding to individual logical blocks and storing application data associated with the individual logical blocks to which the individual physical data blocks of the second set of physical data blocks within the second disruption region of asymmetric memory are identified as corresponding.

23. A memory storage system for storing data for an electronic device, the memory storage system comprising:

a first disruption region of asymmetric memory that includes;

a first set of physical data blocks for storing application data,

a first physical metadata block that is reserved for storing metadata that is related to application data stored in the first set of physical data blocks within the first disruption region of asymmetric memory, and

a second physical metadata block that is reserved for storing a redundant copy of the metadata that is related to the application data stored in the first set of physical data blocks within the first disruption region of asymmetric memory, wherein the first disruption region of asymmetric memory is configured to enable write operations to individual physical data blocks within the first disruption region of asymmetric memory in which writing to an individual physical data block within the first disruption region of asymmetric memory affects the availability of other physical blocks within the first disruption region of asymmetric memory; and

a second disruption region of asymmetric memory that includes;

a second set of physical data blocks for storing application data,

a third physical metadata block that is reserved for storing metadata that is related to application data stored in the second set of physical data blocks within the second disruption region of asymmetric memory, and

a fourth physical metadata block that is reserved for storing a redundant copy of the metadata that is related to the application data stored in the second set of physical data blocks within the second disruption region of asymmetric memory, wherein the second disruption region of asymmetric memory is configured to enable write operations to individual physical data blocks within the second disruption region of asymmetric memory in which writing to an individual physical data block within the second disruption region of asymmetric memory affects the availability of other physical blocks within the second disruption region of asymmetric memory.

25. The memory storage system of claim 23 wherein:

the first physical metadata block is configured to maintain a first log for storing a first set of metadata entries that are related to write operations performed on individual physical data blocks of the first set of physical data blocks within the first disruption region of asymmetric memory, that identify individual physical data blocks of the first set of physical data blocks within the first disruption region of asymmetric memory as corresponding to individual logical blocks and storing application data associated with the individual logical blocks to which the individual physical data blocks of the first set of physical data blocks within the first disruption region of asymmetric memory are identified as corresponding, and that specify relative times at which the application data associated with individual logical blocks was written to the individual physical data blocks of the first set of physical data blocks within the first disruption region of asymmetric memory; and

the second physical metadata block is configured to maintain a second log for storing a second set of metadata entries that are related to write operations performed on individual physical data blocks of the second set of physical data blocks within the second disruption region of asymmetric memory, that identify individual physical data blocks of the second set of physical data blocks within the second disruption region of asymmetric memory as corresponding to individual logical blocks and storing application data associated with the individual logical blocks to which the individual physical data blocks of the second set of physical data blocks within the second disruption region of asymmetric memory are identified as corresponding, and that specify relative times at which the application data associated with individual logical blocks was written to the individual physical data blocks of the second set of physical data blocks within the second disruption region of asymmetric memory.

26. The memory storage system of claim 23 wherein:

one or more individual physical data blocks of the first set of physical data blocks within the first disruption region of asymmetric memory are configured to store data associated with individual logical blocks of a logical volume; and

one or more individual physical data blocks of the second set of physical data blocks within the second disruption region of asymmetric memory are configured to store data associated with individual logical blocks of the logical volume.

27. The memory storage system of claim 23 further comprising a volatile memory component that is different from the first disruption region of asymmetric memory and the second disruption region of asymmetric memory, the volatile memory component including a volume information table that is configured to map individual logical blocks of the logical volume to corresponding individual physical data blocks of the first and second sets of physical data blocks within the first and second disruption regions of asymmetric memory that store data associated with the individual logical blocks to which they correspond.

28. The memory storage system of claim 27 wherein the logical volume includes a number of logical blocks, the memory storage system further comprising a volume metadata structure that is configured to store metadata related to the logical volume, the metadata related to the logical volume including:

a name for the logical volume;

the number of logical blocks within the logical volume; and

a relative time at which the logical volume was created.

29. The memory storage system of claim 26 wherein:

the first disruption region of asymmetric memory is a first bank of an asymmetric memory component; and

the second disruption region of asymmetric memory is a second bank of the asymmetric memory component.