WO2013094914A1

WO2013094914A1 - Apparatus and method for indicating flash memory life

Info

Publication number: WO2013094914A1
Application number: PCT/KR2012/010700
Authority: WO
Inventors: 차재혁; 강수용; 원유집; 이태화; 정호영; 윤성로; 최종무
Original assignee: 한양대학교 산학협력단
Priority date: 2011-12-23
Filing date: 2012-12-10
Publication date: 2013-06-27

Abstract

The present invention relates to an apparatus and method for indicating flash memory life. While data is being stored in a flash memory, the number of writes in a plurality of blocks of the flash memory increases. The amount of flash memory life is calculated on the basis of the number of write times in the plurality of blocks. The calculated amount of life can be transmitted to a host. In addition, when the calculated amount of life is greater than a threshold value, a signal providing notice that the life of the flash memory has reached a dangerous level can be output.

Description

Devices and devices providing life indicators of flash memory

The following embodiments relate to flash memory, and more particularly, a method and apparatus for providing a life indicator of a flash memory are disclosed.

Flash memory has a limited lifetime, especially in the writing of data. The flash memory includes a plurality of blocks, and the number of writes for each block is limited.

Due to the short life of the flash memory, loss of data may occur. Various software techniques, such as wear-leveling, can be used to overcome this lifetime problem.

The problem of lifespan is caused by the characteristics of flash memory. Thus, although the lifetime of flash memory can be extended by software techniques, the limitations of software techniques also exist clearly.

In order to prevent the data stored in the flash memory from being damaged due to the short life of the flash memory, a method of providing information on the life of the flash memory is required.

One embodiment may provide an apparatus and method for enabling a user to check the lifetime value of a flash memory.

One embodiment may provide an apparatus and a method for backing up data stored in a flash memory according to a lifetime value of the flash memory.

The storage device may include a flash memory storing data and a controller configured to calculate a life value of the flash memory based on the number of writes of a plurality of blocks of the flash memory.

There may be a plurality of flash memories.

The lifetime value may be a value within a predetermined range.

The controller may calculate the life value based on a dispersion value of the write times and a maximum value of the write times.

The controller may calculate the life value based on the number of writes of blocks having a write count greater than or equal to a threshold value among the plurality of blocks.

The threshold value may be determined based on a maximum number of writes of a block of the flash memory.

The storage device may further include a connection unit connected to a host to transmit the lifetime value to the host.

The controller may transmit the calculated lifetime value to the host through the connection unit if the calculated lifetime value is greater than or equal to a threshold value.

The storage device may further include a display unit for outputting light or sound.

The controller may control the display unit to output the light or the sound when the calculated life value is greater than or equal to a threshold value.

The storage device of claim 1, further comprising: storing data in a flash memory and calculating a lifetime value of the flash memory based on the number of writes of the plurality of blocks of the flash memory. An operation method of may be provided.

The lifetime value may be calculated based on a variance value of the write times and a maximum value of the write times.

The life value may be calculated based on the number of writes of blocks whose write count is greater than or equal to a threshold value among the plurality of blocks.

The method of operating a storage device using the flash memory may further include transmitting the calculated life span value to a host using the storage device when the calculated life span value is greater than or equal to a threshold value.

The method of operating a storage device using the flash memory may further include outputting light or sound when the calculated life value is greater than or equal to a threshold value.

In another aspect, a storage device including a flash memory and a processor for controlling the storage device, the storage device of the storage device calculated based on the number of writes of a plurality of blocks of the flash memory; An electronic device may be provided that transmits a lifetime value to the processor, and wherein the processor determines whether to perform backup of data in the storage device based on the lifetime value.

The electronic device may further include a backup storage device.

The processor may read the data in the storage device and write the data in the backup storage device when the backup is determined.

In another aspect, the storage device calculates a calculated lifetime value of the storage device based on the number of writes of a plurality of blocks of flash memory in the storage device, wherein the storage device calculates the calculated lifetime value. Transmitting to the processor; And determining, by the processor, whether to back up data in the storage device based on the calculated lifetime value.

An apparatus and method are provided for enabling a user to check the lifetime value of a flash memory. The user can determine the lifetime value of the flash memory and can respond according to the threat of the lifetime value.

According to the lifetime value of a flash memory, an apparatus and method for backing up data stored in a flash memory are provided.

1 is a block diagram of a storage device according to example embodiments.

2 is a flowchart of a method of operating a storage device using a flash memory, according to an exemplary embodiment.

3 is a block diagram of an electronic device according to an exemplary embodiment.

4 is a signal flowchart of a method of operating an electronic device according to an exemplary embodiment.

Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. Like reference numerals in the drawings denote like elements.

The number of times data is written to a block of the flash memory is equal to the number of times data is deleted from the block or is proportional to the number of times the data is deleted. Accordingly, the term "write count" and the term "delete number" hereinafter may be used with the same meaning and may be replaced with each other.

1 is a block diagram of a storage device according to example embodiments.

The storage device 100 may include a connector 110, a controller 120, a flash memory 130, and an indicator 140.

The storage device 100 may include a universal serial bus (USB) storage device, a flash memory card, a solid state drive (SSD), an MP3 player, a mobile phone ( The device may be a device in which a flash memory such as a mobile phone or a tablet is embedded and connected to a host. The host is an electronic device such as a personal computer (PC), and may be a device that writes data to or reads data from the storage device 100 connected thereto. .

The connection unit 110 may connect the storage device 100 to a host. The connection unit 110 may provide an interface of the storage device 100 to the host.

The connection unit 110 may be an interface port of a predetermined standard such as USB, an IEEE 1394, an AT, or the like. Alternatively, the connection unit 110 may be a chip for data transmission between the host and the storage device 100. The connection unit 110 may transmit data output from the controller 120 to the host, and may transmit data output from the host to the controller 120. For example, the connection unit 110 may be connected to the host to transmit the lifetime value calculated by the control unit 120 to the host.

The connection unit 110 may be a port or an interface component that provides a wired / wireless network such as an Ethernet port, a blue tooth chip, or a Wi-Fi chip. The host and the storage device 100 may be connected to each other through a wired or wireless network.

The controller 120 may access data in the flash memory 130 at the request of the host. The controller 120 may read data requested by the host from the flash memory 130 and transmit the data to the host through the connection unit 110. In addition, the controller 120 may write data transmitted by the host to the flash memory 130. The controller 120 may perform a function of a flash translation layer (FTL).

The flash memory 130 may store data. The flash memory 130 may include a plurality of blocks. In FIG. 1, as a plurality of blocks, a first block 132, a second block 134, a third block 136, and a fourth block 138 are illustrated.

Each of the blocks may be a unit for accessing data such as read, write, update, and delete, or a unit of operation. That is, the controller 120 may access data in the flash memory 130 on a block basis and may provide an operation on the flash memory 130. The block may be different from the unit of data requested by the host.

Each of the blocks may have a limited number of writes. Write times of blocks may be managed by the controller 120 as metadata. The limited number of writes may be due to the characteristics of the flash memory 130. The number of writes of the block may increase by one each time new data is written to the block. The controller 120 may perform mapping between the logical address used by the host and the physical address used to access the flash memory 130. Thus, with the logical address of the data that the host has requested to write, the host cannot actually know in which block of the flash memory 130 the data was written. In addition, the controller 120 may provide various functions for reducing writing to a block, such as buffering, caching, and wear-leveling. Therefore, the host may not know which block of the flash memory 130 has been written by the request, and may not know whether the data has been actually written to the flash memory 130.

When the number of writes of at least one of the blocks reaches a maximum value, additional writing may not be possible in the above block, and the entire flash memory 130 may no longer be used.

There may be a plurality of flash memories 130. Each of the plurality of flash memories may include a plurality of blocks. The lifetime value to be described below may be calculated for each of the plurality of flash memories. Also, a plurality of physical flash memories may be regarded as one flash memory 130.

The display unit 140 may indicate that the life of the flash memory 130 has reached a dangerous level. The display unit 140 may output light or sound. When the life span of the flash memory 130 reaches a dangerous level, the controller 120 outputs light or sound through the display unit 140 to a degree that the life of the flash memory 130 is dangerous to a user of the storage device 100. You can tell that you have reached.

The display unit 140 may be a light emitting diode (LED) for outputting light or a speaker for outputting sound.

In operation 210, the controller 120 may store data in a flash memory.

The controller 120 may store data in a block selected to process a data access request of a host among a plurality of blocks of the flash memory 130. The controller 120 may update the write count of the selected block. The number of writes of the selected block may be managed as metadata. The metadata may be stored in a particular block of flash memory 130 and may be stored in a cache (not shown) of storage device 100, such as a random access memory (RAM).

In operation 220, the controller 120 may receive a request for the lifetime value of the storage device 100 from the host through the connector 110. Step 220 is optional, and the controller 120 may transmit the calculated lifetime value to the host as needed without the host request.

In operation 230, the controller 120 may calculate a lifetime value of the flash memory 130 or the storage device 100 based on the number of writes of the plurality of blocks of the flash memory 130.

The controller 120 may calculate a lifetime value based on Equations 1 to 2 below.

The set T may be a set of write times of a plurality of blocks of the flash memory 130. The write count may be an integer of 0 or more, respectively.

The set P may be blocks in which the number of writes is greater than or equal to a first threshold value among the plurality of blocks of the flash memory 130. That is, the controller 120 may calculate a lifetime value based on the number of writes of blocks having a write count greater than or equal to a threshold value among the plurality of blocks of the flash memory 130. The first threshold value may be determined based on the maximum number of writes of a block of the flash memory 130. The first threshold value may be a value obtained by multiplying a maximum number of writes of a block of the flash memory 130 by a correction factor that is a real number greater than 0 and less than or equal to 1. For example, the set P may be defined according to Equation 1 below.

Here, EraseCount _Max may be the maximum number of writes of a block of the flash memory 130. 0.8 may represent an example of a correction factor. x may represent each block of the flash memory 130.

When the number of elements of the set P is 1 or more, the controller 120 may calculate a lifetime value based on Equation 2. When there is no element of the set P , the controller 120 may calculate a lifetime value based on Equation 3.

Here, P _Max may be the maximum value among the elements in the set P. P _Max may be a maximum value among the number of writes of blocks of the flash memory 130.

V may be a variance value of the number of writes of blocks of the flash memory 130. V _Max may be the maximum value of the variance of the write times of the blocks of the flash memory 130. That is, V _Max may be the maximum variance value that the number of writes of blocks of the flash memory 130 may have. For example, when the number of blocks of the flash memory 130 is 2 n , V _Max indicates that the number of writes of n blocks among the blocks of the flash memory 130 is all zero, and the number of writes of the remaining n blocks is EraseCount. _It can be the value of V when _Max . n may be an integer of 1 or more.

s may be a weight. s may be a value capable of adjusting the specific gravity between the left term and the right term of Equation 2. s may be a real number between 0 and 1, inclusive. S may be a real number equal to or greater than 0.5 to calculate meaningful lifetime values.

According to the above description with reference to Equations 1 to 3, the lifetime value calculated by the controller 120 may be a value within a predetermined range. The lifetime value may be a value between 0 and 100, inclusive. The controller 120 may calculate a lifespan value based on at least one of S , P , P _Max , V , V _Max, and EraseCount _Max . The controller 120 may calculate a lifespan value of the flash memory 130 based on a dispersion value of the number of writes of the blocks of the flash memory 130 and at least one of a maximum value of the number of writes. For example, the calculated lifetime value may be proportional to one or more of P _Max and V , and inversely proportional to one or more of V _Max and EraseCount _Max . In addition, the number of writes used to calculate the lifetime value may be limited to only the number of writes above the threshold, as described above with reference to Equation (1).

In operation 240, the controller 120 may compare the calculated lifetime value with the second threshold value. If the calculated lifetime value is greater than or equal to the second threshold value, one or more of

steps

250 and 260 to be described below may be performed. If the calculated lifetime value is less than the second threshold value, the procedure may end.

If the calculated lifetime value is greater than or equal to the second threshold value, in step 250, the controller 120 may transmit the calculated lifetime value to the host using the storage device 100 through the connection unit 110. If the host requested a lifetime value in step 210, step 250 may always be performed without a comparison between the calculated lifetime value and the second threshold value. In addition, step 250 may be performed periodically.

If the calculated lifetime value is greater than or equal to the second threshold value, in step 260, the controller 120 may control the display unit 140 to output light or sound. When light or sound is output by the display unit 140, the user may recognize that the life of the flash memory 130 or the storage device 100 has reached a dangerous level.

The electronic device 300 may be a host described above with reference to FIGS. 1 and 2. That is, the electronic device 300 may be a device using the storage device 100.

The electronic device 300 may include a processor 310, a storage device 100, and a backup storage device 320.

The processor 310 may process operations required for the operation of the electronic device 300 and may control the storage device 100 and the backup storage device 320. The processor 310 may access data stored in the storage device 100 and data stored in the backup storage device 320.

The storage device 100 and the backup storage device 320 may store data of the electronic device 300. The backup storage device 320 can be used to back up the data of the storage device 100. The backup storage device 320 may also be a storage device 100 that uses a flash memory and provides a lifetime value.

In operation 410, the processor 310 may transmit a request for a lifetime value of the storage device 100 to the connection unit 110 of the storage device 100. Step 410 is additional, and the storage device 100 may calculate the lifetime value without an explicit request from the processor 310 and transmit the calculated lifetime value to the processor 310 according to a predefined protocol. .

In operation 420, the controller 120 of the storage device 100 may calculate a lifetime value of the storage device 100. Here, the lifetime value of the storage device 100 may be a lifetime value of the flash memory 130 of the storage device 100. As described above with reference to FIG. 2, the lifetime value of the storage device 100 may be calculated based on the number of writes of a plurality of blocks of the flash memory 120 in the storage device 100.

In operation 430, the control unit 120 of the storage device 100 may transmit the calculated life value to the processor 310 through the connection unit 110. The controller 120 may transmit the calculated lifetime value only to the processor 310 when the calculated lifetime value is greater than or equal to the second threshold value.

In step 440, the processor 310 may indicate the transmitted lifetime value. The transmitted lifetime value may be displayed through an application running on the electronic device 300. The user may recognize the displayed lifetime value and take appropriate measures according to the lifetime value, such as backup of data in the storage device 100.

In operation 450, the processor 310 may determine whether to perform backup of data in the storage device 100 based on the transmitted lifetime value. For example, if the transmitted lifetime value is greater than or equal to the second threshold value, the processor 310 may perform step 450 to be described later.

In operation 460, when a backup is determined, the processor 310 may back up data in the storage device 100 to the backup storage device 320. That is, the processor 310 may read data in the storage device 100 and write the data in the backup storage device 320.

Step 460 may include step 462 and step 464.

In operation 462, the processor 310 may read data in the storage device 100.

In operation 464, the processor 310 may write data read from the storage device 100 into the backup storage device 454.

Steps 462 and 464 may be performed repeatedly until all data required for backup in the storage device 100 is backed up.

The apparatus described above may be implemented as a hardware component, a software component, and / or a combination of hardware components and software components. For example, the devices and components described in the embodiments may be, for example, processors, controllers, arithmetic logic units (ALUs), digital signal processors, microcomputers, field programmable arrays (FPAs), It may be implemented using one or more general purpose or special purpose computers, such as a programmable logic unit (PLU), microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process and generate data in response to the execution of the software. For convenience of explanation, one processing device may be described as being used, but one of ordinary skill in the art will appreciate that the processing device includes a plurality of processing elements and / or a plurality of types of processing elements. It can be seen that it may include. For example, the processing device may include a plurality of processors or one processor and one controller. In addition, other processing configurations are possible, such as parallel processors.

The software may include a computer program, code, instructions, or a combination of one or more of the above, and configure the processing device to operate as desired, or process it independently or collectively. You can command the device. Software and / or data may be any type of machine, component, physical device, virtual equipment, computer storage medium or device in order to be interpreted by or to provide instructions or data to the processing device. Or may be permanently or temporarily embodied in a signal wave to be transmitted. The software may be distributed over networked computer systems so that they may be stored or executed in a distributed manner. Software and data may be stored on one or more computer readable recording media.

The method according to the embodiment may be embodied in the form of program instructions that can be executed by various computer means and recorded in a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the media may be those specially designed and constructed for the purposes of the embodiments, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer readable recording media include magnetic media such as hard disks, floppy disks and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

Although the embodiments have been described by the limited embodiments and the drawings as described above, various modifications and variations are possible to those skilled in the art from the above description. For example, the described techniques may be performed in a different order than the described method, and / or components of the described systems, structures, devices, circuits, etc. may be combined or combined in a different form than the described method, or other components. Or even if replaced or substituted by equivalents, an appropriate result can be achieved.

Claims

A flash memory for storing data; And

A controller configured to calculate a life value of the flash memory based on the number of writes of a plurality of blocks of the flash memory

Including, a storage device.
The method of claim 1,

And the control unit calculates the life value based on a variance value of the write times and a maximum value of the write times.
The method of claim 1,

The controller is further configured to calculate the life value based on the number of writes of blocks having a write count greater than or equal to a threshold value among the plurality of blocks.
The method of claim 3,

And the threshold value is determined based on a maximum number of writes of a block of the flash memory.
The method of claim 1,

A connection unit connected to a host to transmit the lifetime value to the host

The storage device further comprises.
The method of claim 5,

And the control unit transmits the calculated lifetime value to the host through the connection unit if the calculated lifetime value is greater than or equal to a threshold value.
The method of claim 5,

Further comprising a display unit for outputting light or sound,

And the controller controls the display unit to output the light or the sound when the calculated life value is greater than or equal to a threshold value.
Storing data in flash memory; And

Calculating a life value of the flash memory based on the number of writes of a plurality of blocks of the flash memory;

Method of operating a storage device using a flash memory, including.
The method of claim 8,

And wherein the lifetime value is calculated based on a variance value of the number of writes and a maximum value of the number of writes.
The method of claim 8,

And the lifespan value is calculated based on the number of writes of blocks having a write count greater than or equal to a threshold value among the plurality of blocks.
The method of claim 8,

If the calculated lifetime value is greater than or equal to a threshold, transmitting the calculated lifetime value to a host using the storage device;

Further comprising a method of operating a storage device using a flash memory.
The method of claim 8,

Outputting light or sound if the calculated lifetime is greater than or equal to a threshold;

Further comprising a method of operating a storage device using a flash memory.
A storage device including a flash memory; And

A processor controlling the storage device

Including,

The storage device transmits a lifetime value of the storage device calculated based on the number of writes of the plurality of blocks of the flash memory to the processor,

And the processor determines whether to back up data in the storage device based on the lifetime value.
The method of claim 13,

Further comprising a backup storage device,

And the processor reads the data in the storage device and writes the data in the backup storage device when the backup is determined.