System data storage mechanism providing coherency and segmented data loading

• US 10,379,755 B2
• Filed: 10/26/2015
• Issued: 08/13/2019
• Est. Priority Date: 05/22/2012
• Status: Active Grant

• Current Assignee: JP Morgan Chase Bank, N.A. (JP Morgan Chase & Co)
• Original Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Inventors: Lo, Jerry, Suryabudi, Dominic S., Phan, Lan D.
• Primary Examiner(s): Yi, David
• Assistant Examiner(s): Puche, Tahilba O
• Application Number:
  US14/923,000
• Publication Number:
  US 20160048352A1
• Time in Patent Office: 1,387 Days
• CPC Class Codes: G06F 11/1435 using file system or storage system metadata
• CPC Class Codes: G06F 11/1448 Management of the data involved in backup or backup restore
• CPC Class Codes: G06F 11/1458 Management of the backup or restore process
• CPC Class Codes: G06F 11/1469 Backup restoration techniques
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 12/0804 with main memory updating G06F12/0806 takes precedence
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
• CPC Class Codes: G06F 3/0685 Hybrid storage combining heterogeneous device types, e.g. hierarchical storage, hybrid arrays

Abstract

A data storage subsystem is disclosed that implements a process for storing and/or reconstructing system data, such as a system mapping table. In certain embodiments, table pages are systematically copied, or flushed, to non-volatile memory in a progressive manner, according to a fixed ratio of flushed table pages per table update trigger, thereby facilitating write and/or load efficiency. Full or partial reconstruction of a table may be performed within a bounded number of operations based on the size of the table, the ratio implemented, and/or other characteristics.

Claims

1. A method of storing and recovering a segmented system table having y table pages in a data storage system, the method comprising:

in response to updating a first table page of the segmented system table in a volatile memory;

flushing the updated first table page from the volatile memory to a non-volatile memory; and

flushing, from the volatile memory to the non-volatile memory, one or more additional table pages of the segmented system table in the volatile memory based at least on a predetermined ratio of a number of flushed table pages to a number of segmented system table update triggers to keep table pages in the non-volatile memory updated, wherein the one or more additional table pages are different from the first table page;

loading a set of z table pages divided into a plurality of segments from the non-volatile memory to the volatile memory according to individual segments;

determining whether a host data access request accessing an address within a yet-to-be loaded segment of the plurality of segments is pending;

processing a segment containing the address of the host data access request when it is determined that the host data access request is pending and is within the yet-to-be loaded segment of the plurality of segments;

locating and copying into the volatile memory, by individual segment, a most up-to date version of each table page contained in the individual segment; and

recovering the segmented system table using a number of load operations less than or equal to twice a size of the segmented system table measured in segments.

2. The method of claim 1, wherein a first of the individual segments loaded into volatile memory, when no host data access request is pending, comprises a segment of the set of z table pages that were most recently stored to non-volatile memory.

3. The method of claim 1, wherein a first of the individual segments loaded into volatile memory, when no host data access request is pending, comprises an oldest valid table page of the set of z table pages stored in non-volatile memory.

4. A non-volatile storage system comprising:

a non-volatile memory configured to store data;

a volatile memory; and

a controller configured to store and recover a segmented system table having y table pages by;

in response to updating a first table page of the segmented system table in the volatile memory;

flushing the updated first table page from the volatile memory to the non-volatile memory; and

flushing, from the volatile memory to the non-volatile memory, one or more additional table pages of the segmented system table in the volatile memory based at least on a predetermined ratio of a number of flushed table pages to a number of segmented system table update triggers to keep table pages in the non-volatile memory updated, wherein the one or more additional table pages are different from the first table page;

loading a set of z table pages divided into a plurality of segments from a non-volatile memory to a volatile memory according to individual segments;

determining whether a host data access request accessing an address within a yet-to-be loaded segment of the plurality of segments is pending;

processing a segment containing the address of the host data access request when it is determined that a host data access request is pending and is within the yet-to-be loaded segment of the plurality of segments;

locating and copying into the volatile memory, by individual segment, a most up-to date version of each table page contained in the individual segment; and

recovering the segmented system table using a number of operations less than or equal to twice a size of the segmented system table measured in segments.

5. The non-volatile storage system of claim 4, wherein a first of the individual segments loaded into volatile memory, when no host data access request is pending, comprises a segment of the set of z table pages that were most recently stored to non-volatile memory.

6. The non-volatile storage system of claim 4, wherein a first of the individual segments loaded into volatile memory, when no host data access request is pending, comprises an oldest valid table page of the set of z table pages stored in non-volatile memory.