Method and system for recovering storage object records in solid state memory

• US 10,416,904 B1
• Filed: 12/30/2016
• Issued: 09/17/2019
• Est. Priority Date: 12/30/2016
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Inventors: Van Gaasbeck, Richard H.
• Primary Examiner(s): Rones, Charles
• Assistant Examiner(s): Li, Hewy H
• Application Number:
  US15/394,984
• Time in Patent Office: 991 Days
• Field of Search: None
• CPC Class Codes: G06F 11/1441 Resetting or repowering
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/7201 Logical to physical mapping or translation of blocks or pages
• CPC Class Codes: G06F 2212/7211 Wear leveling
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0616 in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0647 Migration mechanisms
• CPC Class Codes: G06F 3/0655 Vertical data movement, i.e. input-output transfer; data movement between one or more hosts and one or more storage devices
• CPC Class Codes: G06F 3/0688 Non-volatile semiconductor memory arrays

Abstract

A method for recovering storage object records in solid state memory. The method includes, for each memory location of a solid state memory region, reading data fragment metadata and identifying, based on the data fragment metadata, a storage object. The storage object occupies a subset of memory locations of the memory locations of the solid state memory region. The method further includes identifying a first and a last memory location of the subset of memory locations, and restoring a storage object record for the storage object, wherein the storage object record comprises variables that enable a logical to physical address translation for the storage object.

Claims

1. A method for recovering storage object records in solid state memory comprising:

for each memory location of a solid state memory region, reading data fragment metadata;

identifying, based on the data fragment metadata, a storage object, wherein the storage object occupies a subset of memory locations of the solid state memory region;

identifying a first memory location and a last memory location of the subset of memory locations; and

restoring a storage object record for the storage object, wherein the storage object record comprises variables that enable a logical to physical address translation for the storage object, wherein restoring the storage object record for the storage object comprises;

for each memory location of the subset of memory locations;

obtaining a raw start location based on a physical address of a memory location of the subset of memory locations and a data fragment offset;

determining a gap location and a start location based on the raw start location obtained for the memory location; and

storing the gap location and the start location in the storage object record.

2. The method of claim 1, further comprising:

receiving a request to read a memory fragment of the storage object, wherein the read request specifies a second memory location of the subset of memory locations, specified using a logical address;

translating the logical address into a second physical address using the variables in the storage object record for the storage object; and

reading the memory fragment from the second memory location using the physical address.

3. The method of claim 1, further comprising:

performing a wear level operation to balance the wear of the subset of memory locations; and

updating the storage object record.

4. The method of claim 1,

wherein the start location for the memory location is configured to track a progression of wear level operations performed for the memory location,

wherein the gap location specifies the memory location of the subset of memory locations, and

wherein the gap location is reserved for performing the wear level operations.

5. The method of claim 1, wherein the data fragment metadata for the memory location comprises:

an object ID that uniquely identifies the storage object; and

a data fragment offset that specifies an initial offset of an associated data fragment relative to the first memory location.

6. The method of claim 1,

wherein determining the gap location comprises making a determination that the raw start location for each memory location is identical, and

based on that determination, setting the gap location to the last memory location of the subset of memory locations.

7. The method of claim 1,

wherein determining the gap location comprises making a determination that the raw start locations are segmented into a first set of raw start locations with a lower value and a second set of raw start locations with a higher value, and

when the raw start locations are segmented into the first set of raw start locations with the lower value and the second set of raw start locations with the higher value:

setting the gap location to the memory location associated with the last raw start location in the first set of raw start locations.

8. A system comprising:

a storage module comprising a storage module controller and solid state memory, wherein the storage module controller;

reads data fragment metadata for each memory location of a solid state memory region in the solid state memory;

identifies, based on the data fragment metadata, a storage object, wherein the storage object occupies a subset of memory locations of the solid state memory region;

identifies a first memory location and a last memory location of the subset of memory locations; and

restores a storage object record for the storage object, wherein the storage object record comprises variables that enable a logical to physical address translation for the storage object, wherein restoring the storage object record for the storage object comprises;

for each memory location of the subset of memory locations;

obtaining a raw start location based on a physical address of a memory location of the subset of memory locations and a data fragment offset;

determining a gap location and a start location based on the raw start locations obtained for the memory location; and

storing the gap location and the start location in the storage object record.

9. The system of claim 8,

wherein the start location for the memory location is configured to track a progression of wear level operations performed for the memory location,

wherein the gap location specifies the memory location of the subset of memory locations, and

wherein the gap location is reserved for performing the wear level operations.

10. The system of claim 8, wherein the data fragment metadata for the memory location comprises:

an object ID that uniquely identifies the storage object; and

a data fragment offset that specifies an initial offset of an associated data fragment relative to the first memory location.

11. The system of claim 8,

wherein determining the gap location comprises making a determination that the raw start location for each memory location is identical, and

based on that determination, setting the gap location to the last memory location of the subset of memory locations.

12. The system of claim 8,

wherein determining the gap location comprises making a determination that the raw start locations are segmented into a first set of raw start locations with a lower value and a second set of raw start locations with a higher value, and

when the raw start locations are segmented into the first set of raw start locations with the lower value and the second set of raw start locations with the higher value:

setting the gap location to the memory location associated with the last raw start location in the first set of raw start locations.

13. A non-transitory computer readable medium comprising computer readable program code, which when executed by a computer processor enables the computer processor to:

read data fragment metadata, for each memory location of a solid state memory region;

identify, based on the data fragment metadata, a storage object, wherein the storage object occupies a subset of memory locations of the solid state memory region;

identify a first memory location and a last memory location of the subset of memory locations; and

restore a storage object record for the storage object, wherein the storage object record comprises variables that enable a logical to physical address translation for the storage object, wherein restoring the storage object record for the storage object comprises;

for each memory location of the subset of memory locations;

obtaining a raw start location based on a physical address of a memory location of the subset of memory locations and a data fragment offset;

determining a gap location and a start location based on the raw start locations obtained for the memory location; and

storing the gap location and the start location in the storage object record.

14. The non-transitory computer readable medium of claim 13, wherein the storage object record comprises:

wherein the start location for the memory location is configured to track a progression of wear level operations performed for the memory location,

wherein the gap location specifies a memory location of the subset of memory locations, and

wherein the gap location is reserved for performing the wear level operations.

15. The non-transitory computer readable medium of claim 13, wherein the data fragment metadata for the memory location comprises:

an object ID that uniquely identifies the storage object; and

a data fragment offset that specifies an initial offset of an associated data fragment relative to the first memory location.

16. The non-transitory computer readable medium of claim 13,

wherein determining the gap location comprises making a determination that the raw start location for each memory location is identical, and

based on that determination, setting the gap location to the last memory location of the subset of memory locations.

17. The non-transitory computer readable medium of claim 13,

wherein determining the gap location comprises making a determination that the raw start locations are segmented into a first set of raw start locations with a lower value and a second set of raw start locations with a higher value, and

when the raw start locations are segmented into the first set of raw start locations with the lower value and the second set of raw start locations with the higher value:

setting the gap location to the memory location associated with the last raw start location in the first set of raw start locations.