Tracking intermix of writes and un-map commands across power cycles

• US 9,753,649 B2
• Filed: 03/16/2015
• Issued: 09/05/2017
• Est. Priority Date: 10/27/2014
• Status: Expired due to Fees

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Inventors: Prins, Douglas A., Olbrich, Aaron K., Guan, Huapeng, Weston-Lewis, Graeme, Kulkarni, Anand, Yu, Yipei
• Primary Examiner(s): Chery, Mardochee
• Application Number:
  US14/659,493
• Publication Number:
  US 20160117099A1
• Time in Patent Office: 904 Days
• Field of Search: 711103
• CPC Class Codes: G06F 11/1441 Resetting or repowering
• CPC Class Codes: G06F 11/1471 involving logging of persistent data for recovery
• 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 2212/7205 Cleaning, compaction, garbage collection, erase control
• 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
• 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 3/064 Management of blocks
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/0688 Non-volatile semiconductor memory arrays

Abstract

Systems, methods and/or devices are used to enable tracking intermix of writes and un-map commands across power cycles. In one aspect, the method includes (1) receiving, at a storage device, a plurality of commands from a host, the storage device including non-volatile memory, (2) maintaining a log corresponding to write commands and un-map commands from the host, (3) maintaining a mapping table in volatile memory, the mapping table used to translate logical addresses to physical addresses, (4) saving the mapping table, on a scheduled basis that is independent of the un-map commands, to the non-volatile memory of the storage device, (5) saving the log to the non-volatile memory, and (6) upon power up of the storage device, rebuilding the mapping table from the saved mapping table in the non-volatile memory of the storage device and from the saved log in the non-volatile memory of the storage device.

Claims

1. A method of managing a storage system, the method comprising:

receiving, at a storage device of the storage system, a plurality of commands from a host to which the storage device is operatively coupled, the plurality of commands from the host including write commands and un-map commands, the storage device including non-volatile memory;

maintaining a log corresponding to the write commands and un-map commands from the host;

maintaining a mapping table in volatile memory, the mapping table used to translate logical addresses in a logical address space available to the host to physical addresses in a physical address space of the storage device, wherein the log is distinct from the mapping table;

saving the mapping table, on a scheduled basis that is independent of the plurality of commands from the host, to the non-volatile memory of the storage device;

saving the log to the non-volatile memory of the storage device; and

upon power up of the storage device, rebuilding the mapping table from the saved mapping table in the non-volatile memory of the storage device and from the saved log in the non-volatile memory of the storage device.

2. The method of claim 1, wherein saving the mapping table includes storing in the non-volatile memory a position pointer to a position in the log.

3. The method of claim 1, wherein:

saving the mapping table includes storing a plurality of distinct portions of the mapping table in the non-volatile memory at distinct scheduled times that are independent of the plurality of commands from the host; and

the rebuilding comprises rebuilding the mapping table from the plurality of distinct portions of the mapping table stored in the non-volatile memory and the saved log in the non-volatile memory.

4. The method of claim 1, wherein for write commands, the log includes physical addresses to which data is stored in conjunction with execution of the write commands.

5. The method of claim 1, wherein the log includes an entry for a first un-map command, the entry including information identifying a plurality of logical addresses un-mapped in accordance with the first un-map command.

6. The method of claim 1, wherein the log includes an entry for a first un-map command, the entry including information identifying a range of logical addresses un-mapped in accordance with the first un-map command.

7. The method of claim 1, wherein saving the log to the non-volatile memory includes saving at least a portion of the log to the non-volatile memory in conjunction with a power fail event.

8. The method of claim 1, wherein saving the log to the non-volatile memory includes:

saving at least a first portion of the log to the non-volatile memory responsive to the log satisfying predefined fullness criteria; and

saving a final portion of the log to the non-volatile memory in conjunction with a power fail event.

9. The method of claim 1, wherein the storage device comprises one or more flash memory devices.

10. A storage device, comprising:

non-volatile memory;

one or more processors; and

controller memory storing one or more programs configured for execution by the one or more processors, the one or more programs including instructions for;

receiving, at the storage device, a plurality of commands from a host to which the storage device is operatively coupled, the plurality of commands from the host including write commands and un-map commands;

maintaining a log corresponding to write commands and un-map commands from the host;

maintaining a mapping table in volatile memory, the mapping table used to translate logical addresses in a logical address space available to the host to physical addresses in a physical address space of the storage device, wherein the log is distinct from the mapping table;

saving the mapping table, on a scheduled basis that is independent of the plurality of commands from the host, to the non-volatile memory;

saving the log to the non-volatile memory; and

upon power up of the storage device, rebuilding the mapping table from the saved mapping table in the non-volatile memory and from the saved log in the non-volatile memory.

11. The storage device of claim 10, wherein saving the mapping table includes storing in the non-volatile memory a position pointer to a position in the log.

12. The storage device of claim 10, wherein:

saving the mapping table includes storing a plurality of distinct portions of the mapping table in the non-volatile memory at distinct scheduled times that are independent of the plurality of commands from the host; and

the rebuilding comprises rebuilding the mapping table from the plurality of distinct portions of the mapping table stored in the non-volatile memory and the saved log in the non-volatile memory.

13. The storage device of claim 10, wherein for write commands, the log includes physical addresses to which data is stored in conjunction with execution of the write commands.

14. The storage device of claim 10, wherein the log includes an entry for a first un-map command, the entry including information identifying a plurality of logical addresses un-mapped in accordance with the first un-map command.

15. The storage device of claim 10, wherein saving the log to the non-volatile memory includes saving at least a portion of the log to the non-volatile memory in conjunction with a power fail event.

16. The storage device of claim 10, wherein saving the log to the non-volatile memory includes:

saving at least a first portion of the log to the non-volatile memory responsive to the log satisfying predefined fullness criteria; and

saving a final portion of the log to the non-volatile memory in conjunction with a power fail event.

17. A non-transitory computer-readable storage medium, storing one or more programs configured for execution by one or more processors of a storage device, the one or more programs including instructions for:

receiving, at the storage device, a plurality of commands from a host to which the storage device is operatively coupled, the plurality of commands from the host including write commands and un-map commands, the storage device including non-volatile memory;

maintaining a log corresponding to write commands and un-map commands from the host;

maintaining a mapping table in volatile memory, the mapping table used to translate logical addresses in a logical address space available to the host to physical addresses in a physical address space of the storage device, wherein the log is distinct from the mapping table;

saving the mapping table, on a scheduled basis that is independent of the plurality of commands from the host, to the non-volatile memory;

saving the log to the non-volatile memory; and

upon power up of the storage device, rebuilding the mapping table from the saved mapping table in the non-volatile memory and from the saved log in the non-volatile memory.

18. The storage medium of claim 17, wherein saving the mapping table includes storing in the non-volatile memory a position pointer to a position in the log.

19. The storage medium of claim 17, wherein:

saving the mapping table includes storing a plurality of distinct portions of the mapping table in the non-volatile memory at distinct scheduled times that are independent of the plurality of commands from the host; and

the rebuilding comprises rebuilding the mapping table from the plurality of distinct portions of the mapping table stored in the non-volatile memory and the saved log in the non-volatile memory.

20. The storage medium of claim 17, wherein for write commands, the log includes physical addresses to which data is stored in conjunction with execution of the write commands.

21. The storage medium of claim 17, wherein the log includes an entry for a first un-map command, the entry including information identifying a plurality of logical addresses un-mapped in accordance with the first un-map command.

22. The storage medium of claim 17, wherein saving the log to the non-volatile memory includes saving at least a portion of the log to the non-volatile memory in conjunction with a power fail event.

23. The storage medium of claim 17, wherein saving the log to the non-volatile memory includes:

saving at least a first portion of the log to the non-volatile memory responsive to the log satisfying predefined fullness criteria; and

saving a final portion of the log to the non-volatile memory in conjunction with a power fail event.