Device for prioritized erasure of flash memory

• US 20080059692A1
• Filed: 05/03/2007
• Published: 03/06/2008
• Est. Priority Date: 09/04/2006
• Status: Active Grant

• Current Assignee: Western Digital Israel Limited (Western Digital Corporation)
• Original Assignee: SanDisk IL Ltd. (Western Digital Corporation)
• Inventors: Erez, Eran
• Granted Patent: US 7,975,119 B2
• Time in Patent Office: Days
• US Class Current: 711/103
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory

Abstract

A storage device having prioritized-erasure capabilities including: a memory for storing data, the memory having at least one flash unit, wherein each flash unit has a plurality of blocks; and a controller configured: to write the data into the plurality of blocks; to assign an erasure-priority to each block, wherein the erasure-priority correlates with an erasure-priority of the data; and to erase the data in each block according to the erasure-priority of each block upon receiving an emergency-erase command. Preferably, the controller is configured to perform the writing of the data into the plurality of blocks in an arbitrary order in a first flash unit, and the writing into subsequent flash units is performed in correlation with the order in the first flash unit. Preferably, the erasing includes aborting erasure, before completing the erasure, for at least some of the plurality of blocks.

Claims

1. A non-volatile storage device having prioritized-erasure capabilities, the device comprising:

(a) a storage memory for storing data in the storage device, said storage memory having at least one flash unit, wherein each flash unit has a plurality of blocks; and

(b) a storage-device controller configured;

(i) to write said data into said plurality of blocks;

(ii) to assign an erasure-priority to each said block, wherein said erasure-priority correlates with an erasure-priority of said data; and

(iii) to erase said data in said each block according to said erasure-priority of said each block upon receiving an emergency-erase command.

2. The device of claim 1, wherein said controller is configured to perform said writing on arbitrarily-selected blocks, and said assigning is performed according to said erasure-priority of said data.

3. The device of claim 1, wherein said controller is configured to perform said assigning of said erasure-priority prior to said writing of said data, and said writing is performed according to said erasure-priority of said each block.

4. The device of claim 1, wherein said controller is configured to perform said writing of said data into said plurality of blocks in an arbitrary order in a first said flash unit, and said writing into subsequent said flash units is performed in correlation with said order in said first flash unit.

5. The device of claim 4, wherein said controller is further configured:

(iv) to assign a common erasure-priority to blocks having a common relative position in each respective said flash unit.

6. The device of claim 1, wherein said controller is further configured:

(iv) to store a log of said erasure-priority for said each block; and

(v) to erase said data in said each block according to said erasure-priority stored in said log upon receiving said emergency-erase command.

7. The device of claim 1, wherein said erasing by said controller includes aborting erasure, before completing said erasure, for at least some of said plurality of blocks.

8. A hard-disk drive having prioritized-erasure capabilities, the drive comprising:

(a) a storage memory for storing data in the hard-disk drive, said storage memory having at least two sectors;

(b) a mechanism for assigning an erasure-priority to each said sector, wherein said erasure-priority correlates with an erasure-priority of said data; and

(c) a mechanism for erasing said at least two sectors according to said erasure-priority of said each sector.