Partial garbage collection for fast error handling and optimized garbage collection for the invisible band

• US 10,061,696 B2
• Filed: 05/27/2016
• Issued: 08/28/2018
• Est. Priority Date: 03/19/2014
• Status: Active Grant

• Current Assignee: Sandisk Technologies Incorporated (Western Digital Corporation)
• Original Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Inventors: Jones, Justin, Tomlin, Andrew J., Sweazey, Paul, Lam, Johnny A., Mullendore, Rodney N.
• Primary Examiner(s): Bryan, Jason B
• Application Number:
  US15/166,694
• Publication Number:
  US 20160275012A1
• Time in Patent Office: 823 Days
• CPC Class Codes: G06F 11/073 in a memory management context, e.g. virtual memory or cache management memory management G06F12/00; testing of static memory units G11C29/00
• CPC Class Codes: G06F 11/0793 Remedial or corrective actions recovery from an exception in an instruction pipeline G06F9/3861; by retry G06F11/1402; for recovering from a failure of a protocol instance or entity H04L69/40
• CPC Class Codes: G06F 12/00 Accessing, addressing or allocating within memory systems or architectures digital input from, or digital output to record carriers, e.g. to disk storage units, G06F3/06
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 12/0253 Garbage collection, i.e. reclamation of unreferenced memory
• CPC Class Codes: G06F 2212/1044 Space efficiency improvement
• CPC Class Codes: G06F 2212/7205 Cleaning, compaction, garbage collection, erase control

Abstract

A method for managing garbage collection of memory locations in an DSD having a plurality of dies each having a plurality of memory blocks includes: selecting a physical region of memory to be garbage collected, the selected physical region being a subset of a block management region; and garbage collecting the selected physical region. The garbage collecting includes: determining one or more journals corresponding to the selected physical region, the journal comprising transaction entries indicating what logical data are written to memory locations in the selected physical region; determining whether the memory locations within the physical region contain valid data based on a comparison of information in the journal and a mapping table; and if valid data exists, copying valid data into memory locations in memory regions other than the selected physical region of memory. The selected physical region of memory is erased when the block management region is erased.

Claims

1. A method for managing garbage collection for an invisible band in a data storage device (DSD), the method comprising:

designating an invisible band that comprises a memory address range designed to indicate that logical data has been invalidated;

creating one or more invisible band S-journals for TRIM operations, wherein the one or more invisible band S-journals contains mapping information transaction entries recording what logical data are mapped to a location designed for denoting that logical data has been invalidated;

scheduling garbage collection for the one or more invisible band S-journals by alternating garbage collection on the one or more invisible band S-journals with garbage collection on one or more data band S-journals, wherein the one or more data band S-journals contain mapping information transaction entries indicating what logical data are written to memory locations in a selected physical region of the DSD; and

performing the scheduled garbage collection.

2. The method of claim 1, wherein the one or more invisible band S-journals scheduled for garbage collection contains substantially a same number of entries as the one or more data band S-journals scheduled for garbage collection.

3. The method of claim 1, comprising:

determining whether a first invisible band S-journal scheduled for garbage collection contains valid metadata;

copying the determined valid metadata from first invisible band S-journal to a second invisible band S-journal; and

freeing the first invisible band S-journal for use.

4. A data storage device (DSD), comprising:

a controller;

a plurality of dies, each die comprising a plurality of memory blocks, an invisible band that comprises a memory address range designed to indicate that logical data has been invalidated; and

one or more invisible band S-journals created by TRIM operations, wherein the one or more invisible band S-journal contains mapping information transaction entries recording what logical data are mapped to a location designed for denoting that logical data has been invalidated;

wherein the controller is configured to schedule garbage collection for the one or more invisible band S-journals by alternating garbage collection on the one or more invisible band S-journals with garbage collection on one or more data band S-journals, wherein the one or more data band S-journals contains mapping information transaction entries indicating what logical data are written to memory locations in a selected physical region of the DSD; and

wherein the controller is configured to perform the scheduled garbage collection.

5. The DSD of claim 4, wherein the one or more invisible band S-journals scheduled for garbage collection contains substantially a same number of entries as the one or more data band S-journals scheduled for garbage collection.

6. The DSD of claim 4, wherein the controller configured to:

determine whether a first invisible band S-journal scheduled for garbage collection contains valid metadata;

copy the determined valid metadata from first invisible band S-journal to a second invisible band S-journal; and

free the first invisible band S-journal for use.