JP2008523468A - Non-volatile recording medium erasing system and method - Google Patents

Abstract

A method and system for erasing data from a nonvolatile recording medium includes a nonvolatile recording medium controller, a nonvolatile recording medium, and a CPU. The data pattern used in the erase command is transmitted to the nonvolatile recording medium once. As a result, the amount of data transferred to the nonvolatile recording medium controller is reduced to a minimum. After receiving the erase command, the non-volatile recording medium controller overwrites this data pattern in the erase area.

Description

(Background of the Invention)
1. FIELD OF THE INVENTION The present invention relates to safe and efficient data misconceptions. In particular, the present invention relates to erasing data stored on a recording medium.

2. General Background Many electronic systems rely on non-volatile recording media to store data. The nonvolatile recording medium can be a hard disk drive, a semiconductor flash drive, a PCMCIA card, a PC card, a magnetic tape, or an optical recording medium. Other types of optical recording media can also be used. Advanced security systems such as military use use a complete and secure erasing method to ensure that data once stored in a non-volatile recording medium can never be restored. In addition, lower level security systems utilize complete erasure to protect personal or sensitive data.

  One current method for erasing data is to delete the pointer that points to the target data to be erased. The data is inaccessible through the deleted pointer, but the data remains recorded in memory and is potentially accessible by other means. Therefore, simply erasing the pointer does not safely erase the data from the non-volatile recording medium.

  Overwriting the entire erase area helps to provide a complete erase. In order to overwrite the entire erase area, a predetermined data pattern is recorded in a storage area in the erase area. Thus, the data originally recorded in the erase area is overwritten. The data pattern can include various digits and / or alphanumeric characters. For example, the data pattern can include a sequence of 1s, a sequence of 0s, or a random combination of 1s and 0s.

  In general, if the erase procedure uses only one data pattern, the erase procedure can leave a trace of the previously stored value in a particular storage area. These traces are not easily read, but can be read by using special measures.

(Summary of Invention)
In one aspect of the invention, a method for securely erasing data from a non-volatile recording medium is provided. The erasure area identifier is transmitted from the processor in the computer apparatus to the nonvolatile recording medium controller. This erase area identifier corresponds to a plurality of storage areas in the erase area in the nonvolatile recording medium. The non-volatile recording medium controller is operatively connected to the non-volatile recording medium. The data pattern is also transmitted from the processor in the computer device to the nonvolatile recording medium controller. This data pattern is transmitted in a single transfer. Finally, an erase command is transmitted from the processor in the computer device to the non-volatile recording medium controller. The non-volatile recording medium controller constitutes an instruction to overwrite a plurality of storage areas in the erase area identified by the erase area identifier. Each instruction overwrites the data pattern in a storage area in the erase area identified by the erase area identifier.

  In another aspect of the present invention, the erase area identifier is randomly generated. In another aspect, the user inputs the erase area identifier. In another aspect, the erase area identifier includes a start storage area and a count number of storage areas in the erase area. In another aspect, the erase area identifier defines an erase area using a cylinder-head-sector address scheme. In yet another aspect, the erase area identifier defines an erase area using a logical block addressing scheme.

  In one aspect, the erasure area identifier or the data pattern is pre-stored in a storage device coupled to a processor in the computing device. In another aspect, the data pattern is randomly generated or input by the user. In another aspect, a processor in the computer device generates a signal indicating the state of data in the erasure area of the non-volatile recording medium.

  In another aspect, the non-volatile recording medium is a hard disk. In another aspect, the non-volatile recording medium is a semiconductor PROM memory. In another aspect, the nonvolatile recording medium is a semiconductor flash memory. In another aspect, the non-volatile recording medium is a magnetic tape.

  In another aspect, a method for securely erasing data from a non-volatile recording medium is provided. An erase command is transmitted from the processor in the computer device to the non-volatile recording medium controller. The non-volatile recording medium controller is operatively connected to the non-volatile recording medium. A plurality of instructions for overwriting a plurality of storage areas corresponding to erase areas identified by previously stored erase area identifiers are configured. Each instruction writes a pre-stored data pattern to at least one of the storage areas within the erase area identified by the pre-stored erase area identifier. These erase areas or data patterns are stored in advance in a nonvolatile recording medium.

  In one aspect, a method for securely erasing data from a non-volatile recording medium is provided. An erasure area identifier is transmitted from the processor in the computer device to the nonvolatile recording medium controller, the erasure area identifier corresponds to a plurality of storage areas in the erasure area in the nonvolatile recording medium, and the nonvolatile recording medium controller Operatively connected to a non-volatile recording medium. A data pattern is transmitted from the processor in the computer device to the nonvolatile recording medium controller, and this data pattern is transmitted a number of times less than the number of storage areas in the plurality of storage areas in the erase area. An erasure command is transmitted from the processor in the computer device to the nonvolatile recording medium controller, and the nonvolatile recording medium controller places the data pattern in a plurality of storage areas in the erasure area identified by the erasure area identifier. A plurality of instructions to be overwritten are configured, and each of these instructions is an instruction to write to at least one of the storage areas in the erase area identified by the erase area identifier.

  In one aspect, a non-volatile recording medium erasing system is provided. A processor in the computer device transmits an erase area identifier, a data pattern, and an erase command. The erase area identifier corresponds to a plurality of storage areas in the erase area in the nonvolatile recording medium. A non-volatile recording medium controller receives a transmission from a processor in the computer device. The non-volatile recording medium controller is operatively connected to the non-volatile recording medium and constitutes a plurality of instructions for overwriting a plurality of storage areas in the erasure area identified by the erasure area identifier. Each instruction is an instruction to write the data pattern in at least one of the storage areas in the erase area identified by the erase area identifier.

  In another aspect, the data pattern can be transmitted a single time or a plurality of times less than the number of storage areas in a plurality of storage areas in the erase area. In another aspect, when the erasure area identifier is 0, the data pattern is written to all the storage areas in the nonvolatile recording medium.

  In one aspect, a method for securely erasing data from a non-volatile recording medium is provided. The data pattern and the erase area identifier are transmitted from the processor in the computer device to the nonvolatile recording medium controller in a single transfer. This erase area identifier corresponds to a plurality of storage areas in the erase area in the nonvolatile recording medium. The non-volatile recording medium controller is operatively connected to the non-volatile recording medium. An erase command is transmitted from the processor in the computer device to the non-volatile recording medium controller. The non-volatile recording medium controller constitutes a plurality of instructions for overwriting a plurality of storage areas in the erase area identified by the erase area identifier. Each instruction is an instruction to write the data pattern in at least one of the storage areas in the erase area identified by the erase area identifier.

  Embodiments of the present invention will be described below with reference to the drawings.

  The methods and systems described below provide faster erasure of data stored on non-volatile recording media than previously seen. Usually, erasing data on a non-volatile recording medium includes the use of a data pattern. This data pattern is usually sent to a non-volatile recording medium every time it is written to a storage area. As a result, a very large number of data pattern transfers are required because secure erasure is typically thousands, if not millions, of storage space on a non-volatile recording medium. This is because it includes overwriting. Transfer of each data pattern to the non-volatile recording medium requires a great deal of time. The methods and systems described below reduce the time required to perform a secure erase by reducing the number of transfers of the data pattern to the non-volatile recording medium.

  It will be apparent to those skilled in the art that this erasing method can be applied to many types of non-volatile recording media including optical, magnetic and semiconductor recording media. These and other features are described below.

  FIG. 1A shows a computer system 100 for securely erasing data stored in a nonvolatile recording medium 130. In one embodiment, the non-volatile recording medium 130 includes a controller 120 and a storage module 125. The controller 120 may be a processor of a computer that stores data in the storage module 125 by directing reading and writing of data on the storage module 125. The controller 120 communicates with an external device such as the computer device 140. The computer device 140 communicates with the controller 120 to manage data written to and erased from the storage module 125. The computer device 140 includes a CPU 110 and a random access memory (RAM) 180. The CPU 110 manages the RAM memory 180. The computing device 140 can receive user input through the input / output device 150. Input / output device 150 may be a keyboard, mouse, touch pad, joystick, touch screen, voice recognition system, and the like. The computer system 140 is a personal computer, laptop computer, cellular telephone, personal data assistant (PDA), media player, server, digital video recorder, embedded control system in the media recorder, embedded control in the digital video recorder. System, embedded control system in other electronic devices, and the like.

  In one embodiment, a user enters an erase command to erase specific data from the storage module 125. Computer system 140 receives an erase command entered by the user through input / output device 150. Therefore, the input / output device 150 supplies the command input by the user to the CPU 110. In other embodiments, CPU 110 triggers or generates an erase command.

  The CPU 110 communicates with the controller 120 by sending and receiving various commands relating to data stored in the storage module 125. One such message sent from the CPU 110 to the controller 120 is an erase message.

  The erase message can include an erase command, a data pattern, and an erase area identifier. In one embodiment, the CPU 110 generates a data pattern. In other embodiments, the data pattern is randomly generated from a random number generator. In one embodiment, CPU 110 has a random number generator. In yet another embodiment, the user inputs a data pattern.

  The erase area identifier designates a set of storage areas in which data to be erased in the storage module 125 exists. The erasure data identifier can be input by the user or can be generated by the CPU 110. In one embodiment, the user can enter the name of the file to be deleted. Based on the name input by the user, the CPU 110 searches for an address corresponding to this file in the nonvolatile recording medium. The CPU 110 can generate an erasure area identifier based on the size of the file and the start address in the nonvolatile recording medium.

  In yet another embodiment, an application running on computer device 140 may request erasure of a file, and CPU 110 generates an erasure area identifier based on the address of the file in the non-volatile recording medium. In yet another embodiment, the user specifies an erase area identifier through the input / output device 150.

  The erase area identifier can define the erase area in various ways. In one embodiment, the erase area identifier may be a list of storage areas. In other embodiments, the erase area identifier may be a start storage area and an end storage area. In other embodiments, the erase area identifier may be a starting storage area and a storage count. In other embodiments, the erase area identifier may be a flag that indicates that the data pattern should be written to all writable storage areas on the storage module 125.

  In one embodiment, the delete message is sent from the CPU 110 to the controller 120 once. After receiving this message, the controller 120 writes the data pattern in the storage area corresponding to the erase area identifier in the storage module 125.

  For example, in situations where secure erasure requires erasing 60 gigabytes of non-volatile recording media, the data pattern typically must be transferred to the non-volatile recording medium 60 billion times. If the data pattern is transferred only once, the transfer time is negligible. Therefore, the total erase time is reduced to the time required to write data on the nonvolatile recording medium. In this particular example, the total erase time is reduced by 15 minutes. Furthermore, in this example, 15 minutes are saved for each additional data pattern used. Thus, if a secure erase needs to use the three data patterns 0x55, 0xAA, 0xFF, respectively, as part of the erase, the total time is saved for 45 minutes.

  In yet another embodiment, CPU 110 sends a plurality of erase messages to controller 120. In one embodiment, all erase messages include the same data pattern and different erase area identifiers. Therefore, the number of erase messages is less than the total number of storage areas to be overwritten. For example, the controller 120 receives a first erase message having a first erase region identifier and a first data pattern. The controller 120 starts writing this data pattern onto the storage area of the storage module 125 specified by the first erase area identifier. Following this, the controller 120 receives a second message having a second erase region identifier and a first data pattern. The number of messages sent to the controller is less than the total number of storage areas in the erase area of the storage module 125 specified by the erase area identifier. Therefore, the total transfer time is reduced because not all storage areas require transfer.

  In an alternative embodiment, multiple erasure messages can include the same erasure area identifier and different data patterns. For example, a first erase message overwrites a range of storage with a first data pattern, a second erase message erases the same set of storage with a second data pattern, and a secure erase with multiple data patterns Can be guaranteed. In another embodiment, the first erase message can overwrite the first data pattern in the first range of storage and the second erase message can overwrite the second data pattern in the second range of storage.

  Sending multiple delete messages to the controller 120 allows the controller 120 to write to multiple storages simultaneously. In other embodiments, the controller 120 begins writing to the second erase area before completing the first erase command. As a result of the controller 120 writing to multiple storage areas of the storage module 125 simultaneously, the time required to overwrite the data stored in these storage areas is further reduced.

  In one embodiment, the erasure message does not include a data pattern. The data pattern can be stored in advance in the storage module 125. Therefore, after receiving the delete message, the controller 120 retrieves the data pattern by retrieving the data pattern from the storage module 125. In other embodiments, the storage module stores a set of data patterns that are retrieved by the controller 120. In another embodiment, the data pattern is a hard wire (hardware wiring) on the controller 120.

  In one embodiment, the erase message does not include an erase area identifier because the erase area identifier is pre-stored in the storage module 125. The controller 120 retrieves the erase area from the storage module 125 to obtain the erase area identifier. In other embodiments, the erase area identifier is a hard wire on the controller 120.

  FIG. 1B shows a computer system 101 in which the nonvolatile recording medium is a hard disk drive 130. The computer system 101 includes a computing device 110 that communicates with the hard disk drive 130 by sending and receiving commands related to data storage. The hard disk drive (drive device) 130 includes a hard disk controller 120 that applies write and read commands to the hard disk 170.

  In one embodiment, after the erase message is configured in the CPU 110, the erase message is sent to the hard disk controller 120 in the hard disk drive 130. The hard disk controller 120 analyzes the erase message and identifies parameters included in the erase message, such as an erase command, a data pattern, and an erase area identifier.

  FIG. 2A shows a tubular diagram 200 of the contents of an erasure message sent to a non-volatile recording medium with a cylinder-head-sector (CHS) addressing scheme. In one embodiment, data is written to the erase area of hard disk 170 using the erase message shown in tubular diagram 200. In another embodiment, the erasure message 200 is used to write data to an erasure area of a nonvolatile recording medium having a logical storage structure similar to that of the hard disk 170.

  The erase message includes an erase command, an erase area identifier, and a data pattern. In one embodiment, the erase message uses seven registers. In another embodiment, command register 207 includes a “Fill” command. The name of the “Fill” command indicates that the erase area is filled with the data pattern contained in the feature register 201. It will be appreciated by those skilled in the art that the name of this command can have other variations such as “Erase”, “SecureErase”, “Delete”, “SecureDelete”. it is obvious.

  As shown in FIG. 2A, the erase area identifier can be stored in registers 202-206. In one embodiment, registers 202-206 contain the starting address and the sector count. The start address can be defined by a cylinder number, a head number, and a sector number. The head number is stored in register 206, which includes the drive number in bits 1-4 and the head information in bit 0. The cylinder information is contained in a cylinder high register 205 for cylinder high parameters and a cylinder low register 204 for cylinder low parameters. The cylinder number uses one or both of these registers, depending on the length of the cylinder. The sector number register 203 indicates the first sector for writing. In one embodiment, sector count register 202 indicates the number of sectors to write the same data pattern. In another embodiment, when the sector count is 0, the data pattern is written on the entire nonvolatile recording medium. In another embodiment, when the sector count is the total number of sectors in the nonvolatile recording medium, the data pattern is written on the entire nonvolatile recording medium. This data pattern is included in the feature register 201.

  FIG. 2B shows a tubular diagram 201 of the contents of an erasure message transmitted to a non-volatile recording medium of the logical block addressing (LBA) method. In one embodiment, the erase message shown in tubular diagram 200 is used to write data to the erase area of hard disk 170 (FIG. 1B). In another embodiment, the erasure message 201 is used to write data to an erasure area of a nonvolatile recording medium having a logical storage structure similar to that of the hard disk 170 (FIG. 1B).

  The erase area identifier can be stored in registers 202-206. In one embodiment, the start address is defined by a sector number stored in one of the registers for the erase message. In another embodiment, the starting address is stored in multiple registers for erase messages. In particular, the drive / head register 206, the cylinder high register 205, the cylinder low register 204, and the sector number register 203 are registers used to store the LBA address where the erase area starts. The LBA address can be large enough to use some or all of these registers

  FIG. 3 shows a process 300 for erasing data from a non-volatile recording medium. In processing block 305, a data pattern is set. This data pattern can be set by user input, computer random number generation, computer calculations, and the like. Further, in processing block 310, an erase area identifier is set. Next, in processing block 315, the set erase area identifier, the set data pattern, and the erase command are transmitted to the nonvolatile recording medium. In one embodiment, the data pattern, erase command, and erase area identifier are sent to the hard disk drive controller. In another embodiment, the data pattern, erase command, and erase area identifier are sent to the flash memory controller. In other embodiments, all three of these components can be sent together in a single erasure message. In yet another embodiment, some combination of these three components can be sent in a single erasure message.

  At process block 318, the configuration instruction is executed after receiving the data pattern, erase command, and erase region identifier. The configuration instruction creates a write instruction including the address of the storage area to be overwritten, the data pattern to be used, and the write command. Following this, processing block 320 interprets the write command and writes the data pattern into the storage area pointed to by the write command.

  After the first write, decision block 325 uses logic to determine whether the write should continue. In order to achieve this, the erase area identifier is examined to determine whether the storage area to which the data pattern is to be written remains in the erase area. If such storage remains in the erase area, another write instruction is constructed by processing block 318 and executed by processing block 320. After executing the write instruction in process block 320, the erase area identifier is again examined in decision block 325 to determine if there are more storage areas to write the data pattern. If it exists, another write command is configured and executed for the next storage area, and so on.

  Determining that all storage in the erase area has been (written) can be accomplished in different ways. In one embodiment, a counter is used, which is initialized to a value equal to the storage count value. The counter can be decremented each time the data pattern is written to the storage area. If the counter value becomes 0, there is no more storage area to be overwritten. In another embodiment, the counter can be initialized to a value of 0 and incremented by a value of 1 each time the data pattern is written to storage. If the counter value equals the number of storage areas in the erase area, there is no more storage area to be overwritten.

  Once all storage is overwritten, processing block 330 can send a status signal from the non-volatile recording medium indicating that the secure erase was successful.

  If another erasure is desired, the method 300 is restarted from the beginning. In process block 305, a data pattern is set, in process block 310 an erase area identifier is set, and in process block 315, the data pattern, erase area identifier, and erase command are transmitted to the non-volatile recording medium. Following this, all write instructions are constructed in process block 318 and overwritten in the erase area in process block 320. If a third erasure is desired, the method 300 is restarted from the beginning.

  In one embodiment, the user can determine whether to complete other erasures on the non-volatile recording medium. The user can select the number and sequence of erasure messages. For example, the user can select four consecutive erase messages, each as part of a secure erase procedure, and send it to the hard disk controller 120. Typical data patterns that are continuously written to a hard disk or other non-volatile recording medium are the hexadecimal values 0x55, 0xAA, 0xFF, and 0x00. By successively writing different binary (binary) data patterns to the same storage area, any traces of the original file data values are erased. In other embodiments, the computer device can logically calculate that another erasure is needed and the method 300 can begin again. The computer device has hexadecimal values stored in the memory and can use these values randomly when performing a new erase in the non-volatile recording medium.

  Although the above description includes many specific items, these are not intended to limit the present invention and should be considered as examples of preferred embodiments thereof. The present invention includes any combination or sub-combination of elements from different types and / or examples disclosed herein. It will be apparent to those skilled in the art that these features, and therefore the scope of the invention, are to be construed in light of the claims.

It is a figure which shows the computer system for deleting the data memorize | stored in the non-volatile recording medium safely. It is a figure which shows the computer system whose nonvolatile recording medium is a hard disk drive FIG. 5 is a tubular diagram of the contents of an erase message sent to a cylinder-head-sector addressing hard disk drive. FIG. 4 is a tubular diagram of the contents of an erase message sent to a logical block addressing hard disk drive. It is a flowchart of non-volatile recording medium erasing.

Claims (25)

In a method for securely erasing data from a non-volatile recording medium,
A step of transmitting an erasure area identifier from a processor in a computer device to a non-volatile recording medium controller, wherein the erasure area identifier corresponds to a plurality of storage areas in the erasure area in the non-volatile recording medium; A volatile recording medium controller operatively connected to the non-volatile recording medium;
Transmitting the data pattern from the processor in the computer device to the nonvolatile recording medium controller in a single transfer;
Transmitting an erasure command from the processor in the computer device to the non-volatile recording medium controller, wherein the non-volatile recording medium controller identifies a plurality of storage areas in the erasure area identified by the erasure area identifier; A plurality of instructions overwriting each of said instructions, each instruction being an instruction to write to at least one of said plurality of storage areas within said erase area identified by said erase area identifier A data erasing method for a non-volatile recording medium.   The method of claim 1, wherein the erasure area identifier is randomly generated.   The method of claim 1, wherein a user inputs the erasure area identifier.   The method of claim 1, wherein the erase area identifier includes a starting storage area and a storage count in the erase area.   The method of claim 1, wherein the erase area identifier defines the erase area in a cylinder-head-sector addressing scheme.   The method of claim 1, wherein the erase area identifier defines the erase area by a logical block addressing scheme.   The method of claim 1, wherein the erasure area identifier is pre-stored in a storage device coupled to the processor in the computing device.   The method of claim 1, wherein the data pattern is randomly generated.   The method of claim 1, wherein a user inputs the data pattern.   The method of claim 1, wherein the data pattern is pre-stored in a storage device coupled to the processor in the computing device.   The method according to claim 1, wherein the nonvolatile recording medium is a hard disk.   The method of claim 1, wherein the non-volatile recording medium is a semiconductor PROM memory.   The method according to claim 1, wherein the nonvolatile recording medium is a semiconductor flash memory.   The method of claim 1, wherein the non-volatile recording medium is a magnetic tape.   The method according to claim 1, wherein the nonvolatile recording medium and the nonvolatile recording medium controller are surrounded by a housing.   2. The method according to claim 1, further comprising a step of transmitting a signal indicating a state of data in the erasure area in the nonvolatile recording medium to the processor in the computer device. In a method for securely erasing data from a non-volatile recording medium,
Sending a command from a processor in a computer device to a non-volatile recording medium controller, wherein the non-volatile recording medium controller is operatively connected to the non-volatile recording medium;
Configuring a plurality of instructions to overwrite a plurality of storage areas corresponding to erase areas identified by pre-stored erase area identifiers, each of the instructions being stored in advance Non-volatile recording comprising: a step of writing a pre-stored data pattern into at least one of the plurality of storage areas in the erase area identified by an erase area identifier How to erase media.   The method according to claim 17, wherein the erasure area is stored in advance in the nonvolatile recording medium.   The method according to claim 17, wherein the data pattern is stored in advance in the nonvolatile recording medium. In a method for securely erasing data from a non-volatile recording medium,
A step of transmitting an erasure area identifier from a processor in a computer device to a non-volatile recording medium controller, wherein the erasure area identifier corresponds to a plurality of storage areas in the erasure area in the non-volatile recording medium; A volatile recording medium controller operatively connected to the non-volatile recording medium;
Transmitting a data pattern from the processor in the computer device to the non-volatile recording medium controller, wherein the data pattern is transmitted a number of times less than the number of storage areas in the plurality of storage areas in the erase area. Sending step;
Transmitting an erasure command from the processor in the computer device to the non-volatile recording medium controller, wherein the non-volatile recording medium controller identifies the plurality of storages in the erasure area identified by the erasure area identifier; Comprising a plurality of instructions overwriting an area, each of said instructions being an instruction to write to at least one of said plurality of storage areas within said erase area identified by said erase area identifier A method for erasing a non-volatile recording medium, comprising: A processor in a computer device;
A non-volatile recording medium erasing system comprising a non-volatile recording medium controller,
The processor in the computer device transmits an erase area identifier, a data pattern, and an erase command, and the erase area identifier corresponds to a plurality of storage areas in the erase area in the nonvolatile recording medium,
The non-volatile recording medium controller receives a transmission from the processor in the computer device, the non-volatile recording medium controller is operatively connected to the non-volatile recording medium, and the non-volatile recording medium controller is Configuring a plurality of instructions to overwrite the plurality of storage areas in the erase area identified by the erase area identifier, wherein each of the instructions is stored in the erase area identified by the erase area identifier; A nonvolatile recording medium erasing system, comprising: an instruction for writing the data pattern in at least one of the areas.   The system of claim 21, wherein the data pattern is transmitted a single time.   The system according to claim 21, wherein the data pattern is transmitted a number of times less than the number of storage areas in the plurality of storage areas in the erasure area.   The system according to claim 21, wherein when the erasure area identifier is 0, the data pattern is written to all storage areas in the nonvolatile recording medium. In a method for securely erasing data from a non-volatile recording medium,
Transmitting a data pattern and an erasure area identifier from a processor in the computer device to the nonvolatile recording medium controller in a single transfer, wherein the erasure area identifier is stored in the erasure area in the nonvolatile recording medium; Corresponding to a plurality of storage areas, wherein the nonvolatile recording medium controller is operatively connected to the nonvolatile recording medium;
Transmitting an erasure command from the processor in the computer device to the non-volatile recording medium controller, wherein the non-volatile recording medium controller includes the plurality of storages in the erasure area identified by the erasure area identifier. Composing instructions to overwrite an area, each of the instructions being an instruction to write the data pattern to at least one of the plurality of storage areas in the erase area identified by the erase area identifier A method for erasing a non-volatile recording medium, comprising:

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