Methods of sanitizing a flash-based data storage device

• US 9,471,232 B2
• Filed: 12/24/2014
• Issued: 10/18/2016
• Est. Priority Date: 03/25/2003
• Status: Expired due to Term

• Current Assignee: Western Digital Israel Limited (Western Digital Corporation)
• Original Assignee: SanDisk IL Ltd. (Western Digital Corporation)
• Inventors: Koren, Rami, Leibinger, Eran, Wiesz, Nimrod, Zilberman, Eugen, Tzur, Ofer, Aharonoff, Sagiv, Teicher, Moredechai
• Primary Examiner(s): Bansal, Gurtej
• Application Number:
  US14/582,995
• Publication Number:
  US 20150153960A1
• Time in Patent Office: 664 Days
• US Class Current: 1/1
• 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 computer implemented method for sanitizing a storage device, comprising:

receiving a sanitize command to sanitize at least a portion of a data storage medium within the storage device, wherein the data storage medium includes a plurality of sub-arrays each having a plurality of storage chips and the portion of the data storage medium includes storage chips from the plurality of sub-arrays;

performing the sanitizing of the plurality of storage chips within the plurality of sub-arrays forming the portion of the data storage medium within the storage device, in response to the sanitize command, the sanitizing executing a sanitize method, wherein the sanitizing is performed in parallel on each of the plurality of storage chips within the plurality of sub-arrays defined in the portion of the data storage medium, the sanitize method defined by one or more sanitize parameters, wherein the sanitize parameters are identified based on the sanitize command;

wherein when an unexpected power interruption occurs during performance of the sanitizing of the storage device,

determining sanitize status of the plurality of storage chips within the plurality of sub-arrays upon powering up the storage device after the unexpected power interruption; and

resuming the sanitizing of the portion of the data storage medium within the storage device, wherein the storage device is a non-volatile storage device.

2. The computer implemented method of claim 1, wherein performing the sanitizing further includes,

setting a sanitize flag indicative of a sanitize status of the storage device;

and

saving at least one sanitize parameter associated with the storage device,

wherein the setting of the sanitize flag and saving of sanitize parameter are performed prior to the sanitizing of the storage device.

3. The computer implemented method of claim 2, wherein determining sanitize status further includes,

interrogating the sanitize flag of the storage device, the sanitize flag defining the sanitize status associated with the sanitizing of each of the plurality of storage chips in the plurality of sub-arrays of the storage device, wherein information provided in the sanitize flag is used for

restarting the sanitizing of the storage chips in each of the plurality of sub-arrays forming the portion of the data storage medium within the storage device from a point of interruption.

4. The computer implemented method of claim 2, further includes resetting the sanitize flag and erasing the at least one sanitize parameter upon successful completion of the sanitizing of the storage device.

5. A computer implemented method for sanitizing a storage device, comprising:

determining sanitize status associated with the sanitizing of the storage device upon powering up of the storage device, wherein the storage device includes a plurality of sub-arrays each having a plurality of storage chips, the sanitize status determined by,

interrogating a sanitize flag associated with each of the plurality of storage chips in each of the plurality of sub-arrays of the storage device, upon powering up of the storage device, wherein the sanitize flag is indicative of sanitize status of each of the plurality of storage chips and is determined by checking a predetermined portion of the respective storage chips for presence of a particular data pattern;

resuming the sanitizing of the plurality of storage chips within the plurality of sub-arrays of the storage device in accordance to sanitize parameters for the storage device, when the sanitize flag of any one or more of the plurality of storage chips indicates an interruption in the sanitizing of the storage device,

wherein the storage device is a non-volatile storage device.

6. The computer implemented method of claim 5, wherein the sanitize flag associated with each of the plurality of storage chips is stored in the non-volatile storage device.

7. The computer implemented method of claim 5, wherein resuming the sanitizing further includes clearing the sanitize flag associated with each of the plurality of storage chips in each of the plurality of sub-arrays, after successful sanitizing of the plurality of storage chips of the storage device.

8. The computer implemented method of claim 5, further includes adjusting the sanitize flag to reflect successful sanitizing of the storage device, upon successfully completing sanitizing of the storage device.

9. The computer implemented method of claim 5, wherein the sanitizing of the storage device is performed upon detection of a predetermined condition, wherein the predetermined condition is one of a physical condition or a logical condition.

10. The computer implemented method of claim 5, further includes verifying successful completion of sanitizing of the storage device based on a verification level parameter defined for the storage device, the verification level parameter identifying a value that is indicative of level of verification to be performed for verifying successful completion of the sanitizing of the storage device.

11. The computer implemented method of claim 10, wherein the level of verification to be performed at the storage device to determine the successful sanitizing includes any one of,

(a) interrogating the sanitize flag associated with each of the storage chips in the plurality of sub-arrays of the storage device;

(b) checking a predetermined portion of the plurality of sub-arrays of the storage device for presence of a data pattern indicative of successful sanitizing of each of the storage chips disposed therein, in addition to the interrogation of the sanitize flag associated with each of the storage chips in the plurality of sub-arrays of the storage device; and

(c) checking each of the plurality of the sub-arrays of the storage device for presence of a data pattern indicative of successful sanitizing of each of the storage chips disposed therein, in addition to the interrogation of the sanitize flag associated with each of the storage chips in the plurality of sub-arrays of the storage device.

12. A data storage device comprising:

a data storage medium;

a controller for performing sanitizing of at least a portion of the data storage medium in response to a sanitize command received from a host system, wherein the data storage medium includes a plurality of sub-arrays each having a plurality of storage chips and the portion of the data storage medium includes storage chips from one or more of the plurality of sub-arrays, wherein the controller is configured to,

(a) determine sanitize status associated with the sanitizing of the portion of the storage medium upon powering up of the storage device, the sanitize status determined by interrogating a sanitize flag associated with each of the plurality of storage chips within each of the plurality of sub-arrays forming the portion of the data storage medium, wherein the sanitize flag is indicative of sanitize status of each of the plurality of storage chips and is determined by checking a predetermined portion of each of the plurality of storage chips in each of the plurality of sub-arrays forming the portion of the data storage medium for presence of a particular data pattern;

(b) resume the sanitizing of the plurality of storage chips within the plurality of sub-arrays forming the portion of the data storage medium based on the sanitize status of the storage device; and

(c) verify successful sanitizing of the portion of the data storage medium based on a verification level parameter defined for the data storage medium, the verification level parameter identifying a value that is indicative of a level of verification to be performed at the data storage medium to verify successful completion of the sanitizing.

13. The data storage device of claim 12, wherein the controller is further configured to adjust the sanitize flag to reflect current sanitizing status of the portion of the data storage medium of the storage device, upon successful completion of sanitizing of the storage device.

14. The data storage device of claim 12, wherein based on the value defined in the verification level parameter, the controller is further configured to perform any one of,

(a) interrogating the sanitize flag associated with each of the plurality of storage chips in each of the plurality of sub-arrays forming the portion of the data storage medium;

(b) checking a predetermined portion of the plurality of sub-arrays of the data storage medium of the storage device for presence of a data pattern indicative of successful sanitizing of each of the storage chips disposed therein, in addition to the interrogation of the sanitize flag associated with each of the plurality of storage chips in the plurality of sub-arrays forming the portion of the data storage medium; and

(c) checking each of the plurality of the sub-arrays of the storage device for presence of a data pattern indicative of successful sanitizing of each of the storage chips disposed therein, in addition to the interrogation of the sanitize flag associated with each of the storage chips in the plurality of sub-arrays of the storage device.

15. The data storage device of claim 12, wherein the controller is configured to perform the sanitizing of the storage device upon detecting a predetermined condition, wherein the predetermined condition is one of a physical condition or a logical condition.