TW201835935A - Control Method for Improving Data Retention on Non-Volatile Storage Device - Google Patents

Abstract

The present invention discloses a control method for improving data retention on a non-volatile storage device. The non-volatile storage device has a control unit, a printed circuit board, a thermal sensor and at least one non-volatile storage unit. The control method has the steps of: supplying power to the non-volatile storage device; saving data into the at least one non-volatile storage unit; recording a time period of saving data into the at least one non-volatile storage unit; reading the temperature delivered from the thermal sensor regularly; auto-freshing the data on the at least one non-volatile storage unit when the time period is longer than a time threshold or the temperature meets a judgment requirement; and increasing the execution frequency of driving the auto-refresh process.

Description

Control method for improving data durability on non-volatile storage device

This case relates to a control method on a non-volatile storage device, and particularly to a control method that can improve the durability of data on a non-volatile storage device.

NAND Flash is a memory used by SSD to carry and store data. SSD can perform various calculations through the Controller. Any detail in these processes may affect the performance and reliability of SSD products. , Stability, etc.

Any characteristic of NAND Flash may become an influence on SSD performance. For example, NAND Flash with different chip types has evolved from SLC and MLC to TLC. The more bits stored in each storage unit, the more likely an error condition will occur and the more likely it is to cause P / E Cycle (write / erase) Frequency) The frequency drops and affects the reliability. The ability of NAND Flash in Data Retention is also a key to whether SSD can replace traditional hard drives.

The storage method of NAND Flash is to store the charge in the floating gate through charge, and determine the storage data through different initial driving voltages, and the charge stored on the floating gate will increase in time and gradually lose, and the speed of the loss will depend on the temperature It is different from P / E Cycle, and as long as the Block is overwritten (Re-write), the potential of the floating gate can be restored. The current practice can be divided into passive inspection and active inspection.

Passive check is when the user requests to read the data of a logical block, the firmware will read the corresponding physical page data stored in the NAND Flash, and check the number of Error Bits of the data while reading. When the number of bits reaches a threshold, the block will be overwritten.

Active inspection is to read all the physical blocks of the storage device and check the number of error bits of the data when the storage device is idle. When the number of error bits of the data reaches a threshold, the block will be overwritten. It takes a lot of time, depending on the capacity of the storage device, it takes a few minutes to tens of minutes, and it cannot function in system applications that are hardly idle or idle for less than a few minutes.

Therefore, most of the current passive inspection methods are mainly used, but this method will only check and overwrite the data blocks that the user often reads, and it is impossible to check the data blocks that the user has not read for a long time. The loss of block data.

Therefore, how to improve the above-mentioned data durability becomes an extremely important issue.

Based on the above objective, the present invention provides a control method for improving data durability on a non-volatile storage device, which includes a control unit, a substrate, a temperature sensing unit, and at least one non-volatile storage Unit, which contains the following steps.

Supply power to the non-volatile storage device.

Write data to the at least one non-volatile storage unit.

Record the data storage time when the data is written to the at least one non-volatile storage unit.

The measured temperature of the temperature sensing unit is periodically read.

When the data storage time is longer than the endurance time threshold or the measured temperature meets the endurance temperature judgment condition, the data is overwritten on the at least one non-volatile storage unit.

Increase the frequency of data overwriting of the automatic periodic driving mechanism.

Preferably, the control method of the present invention further includes: reading the write / erase times of the non-volatile storage device. When the write / erase frequency is higher than the durable access threshold, the data is overwritten on the at least one non-volatile storage unit.

Preferably, the control unit correspondingly increases the data overwrite execution frequency according to the increase in the number of write / erase.

Preferably, the control unit correspondingly increases the data overwrite execution frequency according to the measured temperature change step.

Preferably, the measured temperature is that the temperature sensing unit measures the temperature of the at least one non-volatile storage unit.

Preferably, the temperature sensing unit measures the temperature of the control unit or the substrate.

Preferably, the control method of the present invention further includes re-zeroing the data storage time when the power supply to the non-volatile storage device is stopped.

Preferably, the control method of the present invention further includes suspending the accumulation of the data storage time when the power supply to the non-volatile storage device is stopped until the power is supplied to the non-volatile storage device again.

Some typical embodiments embodying the characteristics and advantages of this case will be described in detail in the following paragraphs. It should be understood that this case can have various changes in different forms, and they all do not deviate from the scope of this case, and the descriptions and illustrations therein are essentially used for explanation, not for limiting this case.

Please refer to FIG. 1, which is a flowchart of the steps of the control method of the first preferred embodiment of the present invention. It relates to a control method for improving data retention on a non-volatile storage device. The non-volatile storage device includes a control unit, a substrate, a temperature sensing unit, and at least one non-volatile storage unit.

In an embodiment, the non-volatile storage device may be a solid state drive or a solid state drive module, the control unit may be a microcontroller, and the non-volatile storage unit may be a NAND Flash, the control unit and The non-volatile storage unit is placed on the substrate, which can basically be a PCB board. It can be understood that there are other electronic components (such as passive components) on the substrate that work together with the control unit and the non-volatile storage unit. In addition, the temperature sensing unit may include a temperature sensor, and the temperature sensing unit may be placed in the control unit or on the substrate. If placed in the controller, it may measure the controller During operation, if a temperature is placed on the substrate, it can measure the general indoor temperature. It is worth mentioning that, in this embodiment, the temperature sensing unit is placed in the control unit for example, but not limited to this.

The control method for improving data durability on a non-volatile storage device of the present invention may include the following steps.

Step S11 is to supply an electric power to the non-volatile storage device. The power supply source can be a computer host, and the computer host and the non-volatile storage device are connected through a power transmission cable, such as a power transmission cable for SATA cables or a power transmission cable for IDE cables.

Step S12 is that a computer host can write a data to at least one non-volatile storage unit in the non-volatile storage device.

Step S13 is a data storage time in which the control unit records data to be written to the non-volatile storage unit, wherein the control unit can record the write time of the data storage time using a register or a non-volatile storage unit , Where the non-volatile storage unit may include a NAND Flash.

Step S14 is that the control unit periodically reads one of the measured temperatures measured by the temperature sensing unit.

Step S15 is determined by the control unit. When the data storage time is longer than a durability time threshold or the measured temperature meets a durability temperature determination condition, the data is overwritten once on the non-volatile storage unit.

In a preferred embodiment, the endurance time threshold can be set to a specific time, such as 12 months, and the endurance temperature judgment condition can be above a high temperature threshold or below a low temperature threshold, when controlled When the unit judges that the current data storage time and the measured temperature match one of them, it can first erase the non-volatile storage unit where the data is located and rewrite the data once, in which the non-volatile data is erased / written The operation of the storage unit can be well-known to those skilled in the art, so it will not be repeated here. Step S16 is that the control unit increases the execution frequency of one of the data overwrites of Auto-Refresh (automatic periodic driving mechanism). In other words, if the initial period of data overwrite execution frequency to execute this automatic periodic drive mechanism is a preset period of 24 months, after the control unit performs data overwrite, the data overwrite execution frequency can be increased to 24 months Twice (ie, once every 12 months) to improve the data durability of this non-volatile storage device. It is worth mentioning that the increased frequency of data overwriting (twice in 24 months) added in this embodiment is only an example, but not limited to this, users can adjust it according to their actual needs.

It is worth mentioning that, in this embodiment, when the power supply to the non-volatile storage device is stopped, the data storage time can be reset to zero by the control unit. For example, if the host computer that supplies power is turned on, the value of this data storage time will be restarted. However, in another embodiment, if the power supply to the non-volatile storage device is stopped, the accumulation of the data storage time may also be suspended by the control unit until power is supplied to the non-volatile storage device again. The accumulation of this data storage time.

In addition, the control unit may correspondingly increase the data overwrite execution frequency according to one of the measured temperature change steps, where the change step distance may be one of the measured temperature changes. For example, after the measured temperature is higher than the high temperature threshold, if the measured temperature is increased by 3 degrees Celsius, the control unit can increase the frequency of the data overwriting line. In this embodiment, the measured temperature changes The inter-distance is used as an example, but not limited to this. It is conceivable that this measurement temperature change level can also include a change mode of the measured temperature, if this change mode meets a When there is a specific rule, the frequency of data overwriting can be increased accordingly.

It can be known in this way that the non-volatile storage device using the control method of the present invention can effectively avoid the problem of loss of charge stored in the floating gate, especially when the non-volatile storage device is located in a special environment, such as Polar climate, or when the computer host supplying power to the non-volatile storage device needs to be maintained in a regular operating state, such as a workstation or a server, and the control unit can also store the data according to the time or this The temperature is measured to adjust the data overwrite execution frequency of the automatic periodic drive mechanism, so the control method of the present invention can effectively improve the data durability of the non-volatile storage device to prevent data errors.

Please refer to FIG. 2, which is a flowchart of the steps of the control method of the second preferred embodiment of the present invention, and refer to FIG. 1 together. The control method includes the following steps.

Step S21 is to supply an electric power to the non-volatile storage device.

Step S22 is that a computer host can write a data to at least one non-volatile storage unit in the non-volatile storage device.

Step S23 is a data storage time when the control unit records the data to be written to the non-volatile storage unit.

Step S24 is that the control unit periodically reads one of the measured temperatures measured by the temperature sensing unit.

Step S25 reads the number of write / erase of one of the non-volatile storage devices.

Step S26 is determined by the control unit. When the data storage time is longer than a durable time threshold or the measured temperature meets a durable temperature judgment condition or the number of write / erase times is higher than a durable access threshold, here Overwrite this data once on the non-volatile storage unit.

In step S27, the control unit increases the execution frequency of one of the data overrides of Auto-Refresh (automatic periodic driving mechanism).

The steps in this embodiment are substantially the same as those in the first embodiment, so they are not repeated here. The difference is that in step S25 and step S26, the control unit will additionally periodically read the number of write / erase and trigger the behavior of overwriting data according to the read number of write / erase. Generally speaking, there is an upper limit on the number of write / erase times available on non-volatile storage devices. For example, the average write / erase frequency of SLC is 60 to 100,000, and the average write / erase frequency of MLC is 3,000 times), and its data durability maintenance time will be inversely proportional to the actual number of write / erase times. Therefore, the greater the number of read / erase times read, it means this The shorter the duration of maintaining the data durability of the non-volatile storage device, then the control unit will automatically perform the action of overwriting data to ensure that data errors are avoided.

In a preferred embodiment, the control unit may correspondingly increase the frequency of data overwriting according to the increase in the number of write / erase cycles. In detail, if the number of write / erase times gradually approaches the upper limit of the non-volatile storage device, the control unit can appropriately increase the frequency of data overwriting.

This case may be modified by any person familiar with the technology as a craftsman, but none of them may be as protected as the scope of the patent application.

S11 ~ S16, S21 ~ S27‧‧‧‧Procedure steps

Figure 1 is a flow chart of the steps of the control method of the first preferred embodiment of the present invention.

Figure 2 is a flow chart of the steps of the control method of the second preferred embodiment of the present invention.

Claims (8)

A control method for improving data durability on a non-volatile storage device. The non-volatile storage device includes a control unit, a substrate, a temperature sensing unit, and at least one non-volatile storage unit, including: supplying an electric power to The non-volatile storage device; writing a data to the at least one non-volatile storage unit; recording a data storage time at which the data is written to the at least one non-volatile storage unit; reading the temperature sensing unit regularly A measured temperature; when the data storage time is longer than a durable time threshold or the measured temperature meets a durable temperature judgment condition, overwriting the data on the at least one non-volatile storage unit; and adding automatic periodic drive One of the mechanisms of data overwrite execution frequency. The control method described in item 1 of the patent application scope further includes: reading the number of write / erase times of one of the non-volatile storage devices; when the number of write / erase times is higher than a durable access threshold, The data is overwritten on the at least one non-volatile storage unit. The control method as described in item 2 of the patent application scope, wherein the control unit correspondingly increases the data overwrite execution frequency according to the increase in the number of write / erase times. The control method as described in item 1 of the patent application scope, wherein the control unit correspondingly increases the execution frequency of the data overwriting according to the step distance of the measured temperature change. The control method as described in item 1 of the patent application range, wherein the measured temperature is the temperature of the at least one non-volatile storage unit measured by the temperature sensing unit. The control method as described in item 1 of the patent application scope, wherein the temperature sensing unit measures the temperature of the control unit or the substrate. The control method described in item 1 of the patent application scope further includes resetting the data storage time to zero when the power supply to the non-volatile storage device is stopped. The control method described in item 1 of the patent application scope further includes suspending the accumulation of the data storage time until the power is supplied to the non-volatile storage device again when the power supply to the non-volatile storage device is stopped.