Methods of sanitizing a flash-based data storage device

• US 20050256997A1
• Filed: 07/01/2005
• Published: 11/17/2005
• Est. Priority Date: 03/25/2003
• Status: Active Grant

• Current Assignee: Western Digital Israel Limited (Western Digital Corporation)
• Original Assignee: M-Systems Flash Disk Pioneers Ltd. (Western Digital Corporation)
• Inventors: Teicher, Mordechai, Koren, Rami, Leibinger, Eran, Tzur, Ofer, Aharonoff, Sagiv, Zilberman, Eugen, Wiesz, Nimrod
• Granted Patent: US 7,089,350 B2
• Time in Patent Office: Days
• US Class Current: 711/103
• CPC Class Codes: G06F 2221/2143 Clearing memory, e.g. to prevent the data from being stolen
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
• CPC Class Codes: G11C 16/102 External programming circuits, e.g. EPROM programmers; In-circuit programming or reprogramming; EPROM emulators
• CPC Class Codes: G11C 16/105 Circuits or methods for updating contents of nonvolatile memory, especially with 'security' features to ensure reliable replacement, i.e. preventing that old data is lost before new data is reliably written
• CPC Class Codes: G11C 16/16 for erasing blocks, e.g. arrays, words, groups

Abstract

A data storage device includes one or more non-volatile, blockwise erasable data storage media and a mechanism for sanitizing the media in response to a single external stimulus or in response to a predetermined physical or logical condition. Optionally, only part of the media is sanitized, at a granularity finer than the blocks of the medium. Setting a flag in an auxiliary nonvolatile memory enables an interrupted sanitize to be detected and restarted. Optionally, a “death certificate” verifying the sanitizing is issued. Preferably, the media are configured in a manner that allows atomic operations of the sanitizing to be effected in parallel.

Claims

1. A method of cleaning a data storage medium, comprising the steps of:

(a) setting a flag that indicates that the data storage medium is to be sanitized; and

(b) subsequent to said setting, beginning a first sanitizing of the data storage medium.

2. The method of claim 1, further comprising the step of:

(c) upon completion of said first sanitizing, clearing said flag.

3. The method of claim 2, further comprising the step of:

(d) before said beginning of said first sanitizing, saving at least one sanitize parameter.

4. The method of claim 3, further comprising the step of:

(e) upon completion of said first sanitizing, erasing said at least one sanitize parameter.

5. The method of claim 1, further comprising the steps of:

(c) upon powering up the data storage medium, checking said flag; and

(d) if said flag is set, beginning a second sanitizing of the data storage medium.

6. The method of claim 5, further comprising the step of:

(e) upon completion of said second sanitizing, clearing said flag.

7. The method of claim 6, further comprising the steps of:

(f) before said beginning of said first sanitizing, saving at least one sanitize parameter.

8. The method of claim 7, further comprising the step of:

(g) upon completion of said second sanitizing, erasing said at least one sanitize parameter.

9. A method of cleaning a data storage medium, comprising the steps of:

(a) sanitizing the data storage medium; and

(b) subsequent to said sanitizing, setting a medium-is-sanitized flag.

10. The method of clam 9, further comprising the step of:

(c) verifying that said sanitizing has been effected.

11. The method of claim 10, wherein said verifying is effected by steps including:

(i) checking that said medium-is-sanitized flag is set.

12. The method of claim 11, wherein said verifying is effected by steps further including:

(ii) checking for a data pattern, stored in at least a portion of the data storage medium, that indicates that said sanitizing has been effected.

13. The method of claim 12, wherein said checking for said data is effected for all of the data storage medium.

14. The method of claim 10, further comprising the steps of:

(d) if said verifying determines that said sanitizing has been effected, issuing a death certificate for the data storage medium.

15. The method of claim 14, wherein said death certificate is based on a verification seed and on a serial number of a device that includes the data storage medium.