A method for testing storage performance of solid state hard disk

Abstract

The present invention discloses a method for testing the storage performance of a solid-state hard disk. The present invention relates to the technical field of hard disk storage testing and solves the technical problem of focusing on some performance indicators and lacking a scientific and reasonable quantitative evaluation method for various performance indicators. The present invention analyzes the performance of a solid-state hard disk from multiple dimensions by testing multiple aspects such as sequential read and write speed, random read and write speed, stability and cache capacity, and can more accurately reflect its comprehensive performance in various practical application scenarios. Various performance indicators are quantified to make the performance evaluation result more intuitive and accurate. At the same time, the storage performance value of the solid-state hard disk is calculated, and the storage performance value judgment interval is divided based on a large amount of market data, the performance of the solid-state hard disk is accurately divided into multiple levels, and corresponding storage performance evaluation is performed according to the calculated storage performance value, thereby providing a decision-making basis with great reference value for users when selecting a solid-state hard disk.

Description

Technical Field

[0001] The present invention relates to the technical field of hard disk storage testing, and in particular to a solid state hard disk storage performance testing method. Background Art

[0002] With the rapid development of information technology, solid-state drives (SSDs) have been widely used in the field of computer storage due to their advantages such as fast data reading and writing speeds, low power consumption and strong shock resistance. Different application scenarios have different performance requirements for SSDs.

[0003] According to the patent application with application number CN202410550913.4, a solid-state hard disk performance test data processing method, device, equipment and storage medium are disclosed, and the method includes: performing data transmission performance testing and parameter collection on the solid-state hard disk based on multiple workload environments to obtain multiple data transmission performance test parameter sets; performing feature selection on the multiple data transmission performance test parameter sets to obtain a data transmission performance feature subset for each workload environment; performing fractal dimension calculation on the data transmission performance feature subset to obtain a fractal dimension calculation result for each workload environment.

[0004] However, some existing SSD storage performance testing methods, when used, traditional testing methods often only focus on some performance indicators. There is a lack of scientific and reasonable quantitative evaluation methods for each performance indicator, and it is impossible to accurately determine the grade division of different performance levels. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a solid-state hard disk storage performance testing method, which solves the problem of focusing on some performance indicators and lacking a scientific and reasonable quantitative evaluation method for each performance indicator.

[0006] To achieve the above objectives, the present invention is implemented by the following technical solution: a method for testing the storage performance of a solid state hard disk, the method specifically comprising the following steps:

[0007] Determine the test content of the solid-state drive to be tested, and the test content includes sequential read and write speed test, random read and write speed test, stability and cache capacity test;

[0008] The sequential reading speed and the sequential writing speed are analyzed, and the sequential reading speed and the sequential writing speed are calculated to obtain the total sequential reading and writing speed assignment;

[0009] The random read and write speeds are analyzed by the 4K random read speed and the 4K random write speed, and the total random read and write speed value is obtained by calculating the sum of the values ​​of the 4K random read speed and the 4K random write speed;

[0010] By analyzing the write amplification rate, P / E cycle times and temperature environment impact of the SSD, the comprehensive assignment and environmental assignment are obtained, and the stability assignment of the SSD is determined by combining the two. Then, the cache capacity index of the SSD is calculated by combining the cache hit rate, read and write speed and response time of the SSD. At the same time, the sum of the stability assignment and the cache capacity index is calculated to obtain the comprehensive capacity value.

[0011] The storage performance value is obtained by comprehensively calculating the total assigned sequential read and write speeds, the total assigned random read and write speeds, and the comprehensive capability value, and the storage performance of the solid state drive is determined based on the storage performance value to generate rating information.

[0012] As a further solution of the present invention, the total value of the sequential read and write speed is calculated as follows:

[0013] Analyze the sequential reading speed, obtain the sequential reading speed corresponding to the current solid state drive and record it as Vs, generate a judgment interval according to the sequential reading speeds of different solid state drives, and perform corresponding value assignment processing on the judgment interval;

[0014] Then, the sequential read speed Vs is matched with the judgment interval to obtain the sequential read speed value corresponding to the current solid state drive, which is recorded as Fs;

[0015] Analyze the sequential write speed to obtain the sequential write speed corresponding to the current solid-state drive and record it as Vx. Similarly, the sequential read speed is analyzed and the sequential write speed of the current solid-state drive is assigned a value and recorded as Fx.

[0016] Substitute the obtained assignment Fs and assignment Fx into the formula , calculate the total value F1 of the current SSD sequential read and write speed, where a and b are the weight ratios corresponding to the sequential read speed and sequential write speed, respectively, and a+b=1.

[0017] As a further solution of the present invention, the total random read / write speed assignment is calculated as follows:

[0018] The current 4K random read speed of the solid state drive is obtained, recorded as Vd, and the IOPS value is obtained at the same time, and the evaluation level corresponding to the current solid state drive is determined according to the obtained 4K random read speed and IOPS value, and the corresponding 4K random read speed value is obtained, recorded as Fd;

[0019] Next, obtain the 4K random write speed and the corresponding IOPS value. Similarly, the 4K random read speed analysis method is used to determine the evaluation level of the current SSD corresponding to the 4K random write speed, and obtain the corresponding value Fg. Then substitute the obtained 4K random read speed value Fd and 4K random read speed value Fg into the formula The total assigned value F2 of the current SSD random read and write speed is calculated.

[0020] As a further solution of the present invention, the specific calculation method of the solid state hard disk stability assignment is as follows:

[0021] Calculate the write amplification of the current solid-state hard disk, match the calculated write amplification with the corresponding evaluation interval, and obtain the corresponding write amplification value, then obtain the P / E cycle number of the current solid-state hard disk, and determine the evaluation level according to the corresponding P / E cycle number, and determine the corresponding P / E cycle number value, then calculate the sum of the values ​​of the write amplification value and the P / E cycle number value as a comprehensive value;

[0022] Obtain the data loss rate and read / write error rate corresponding to the high temperature environment and low temperature environment of the solid state drive to determine the corresponding environmental rating assignment, then calculate the numerical mean of different environmental rating assignments, and use the obtained mean as the environmental assignment;

[0023] The obtained comprehensive assignment and environmental assignment are numerically summed to obtain the stability assignment of the current solid state drive.

[0024] As a further solution of the present invention, the specific calculation method of the solid state drive cache capacity index is as follows:

[0025] The cache hit rate, read / write speed, and response time are quantified and recorded as H, S, and R respectively. Then, the quantized cache hit rate H, read / write speed S, and response time R are substituted into the formula The cache capacity index C corresponding to the solid-state drive is calculated, and Smax is the highest read and write speed of the same type of solid-state drive, and Rmax is the longest response time of the same type of solid-state drive. are the weight coefficients of cache hit rate, read / write speed and response time respectively, and .

[0026] As a further solution of the present invention, the specific calculation method of the comprehensive capability value of the solid state drive is:

[0027] The obtained stability assignment and cache capacity index C are summed to obtain the comprehensive capacity value of the current solid state drive.

[0028] As a further solution of the present invention, the specific calculation method of the solid state hard disk storage performance value is:

[0029] Substitute the total sequential read / write speed value, 4K random read / write speed value, and comprehensive capability value into the formula The storage performance value P of the solid-state drive is calculated, where Q is the comprehensive capability value of the solid-state drive, and F1 and F2 are the total sequential read and write speed values ​​and the 4K random read and write speed values, respectively.

[0030] As a further solution of the present invention, the specific method of generating rating information is:

[0031] The obtained storage performance value P is matched with the corresponding storage performance value judgment interval, and the storage performance value judgment interval is calculated based on the data of different types of solid-state drives on the market. The judgment level of the current solid-state drive is determined based on the storage performance value judgment interval, and the corresponding rating information is generated.

[0032] The present invention provides a method for testing the storage performance of a solid state hard disk. Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention analyzes the performance of solid-state drives from multiple dimensions by testing sequential read and write speeds, random read and write speeds, stability, cache capacity and other aspects, and can more accurately reflect its comprehensive performance in various practical application scenarios. It quantifies various performance indicators to make performance evaluation results more intuitive and accurate. At the same time, the storage performance value of the solid-state drive is calculated, and the storage performance value judgment interval is divided based on a large amount of market data. The performance of the solid-state drive is accurately divided into four levels: high-level performance, intermediate performance, normal performance and low-level performance. The corresponding storage performance evaluation is performed according to the calculated storage performance value, which provides users with a decision-making basis with great reference value when selecting a solid-state drive. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a step method diagram of the present invention;

[0035] Figure 2 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] For example, see Figure 1 The present application provides a method for testing the storage performance of a solid state drive, the method specifically comprising the following steps:

[0038] Step S1, obtaining a solid-state hard disk to be tested, and obtaining test content corresponding to the solid-state hard disk, and the test content includes sequential read and write speed test, random read and write speed test, stability and cache capacity test.

[0039] Step S2: Analyze the sequential read and write speeds in the solid state drive test content, wherein the sequential read and write speeds include sequential read speed and sequential write speed, and the two are analyzed separately. The specific analysis method is as follows:

[0040] The sequential read speed is analyzed to obtain the sequential read speed corresponding to the current solid-state drive and recorded as Vs. At the same time, a judgment interval is generated according to the sequential read speeds of different solid-state drives, and the judgment interval is assigned a corresponding value. For example, according to the common sequential read speed ranges of different types of solid-state drives on the market, multiple judgment intervals are divided, and each interval is assigned a corresponding score, such as:

[0041] Interval 1: The sequential read speed is less than 1000 MB / s and is assigned a score of 1.

[0042] Range 2: Sequential read speed is between 1000MB / s (inclusive) and 2000MB / s, with a value of 2 points.

[0043] Range 3: Sequential read speed is between 2000MB / s (inclusive) and 3000MB / s, with a value of 3 points.

[0044] Interval 4: Sequential read speed is greater than 3000MB / s, with a score of 4.

[0045] Then, the sequential read speed Vs is matched with the judgment interval to obtain the sequential read speed value corresponding to the current solid state drive, which is recorded as Fs;

[0046] Analyze the sequential write speed to obtain the sequential write speed corresponding to the current solid-state drive and record it as Vx. Similarly, the sequential read speed is analyzed and the sequential write speed of the current solid-state drive is assigned a value and recorded as Fx.

[0047] Substitute the obtained assignment Fs and assignment Fx into the formula , calculate the total value F1 of the current solid-state hard disk sequential read and write speed, where a and b are the weight ratios corresponding to the sequential read speed and sequential write speed, and a+b=1. The specific value is determined by the operator based on the actual situation.

[0048] For example, in a specific example, after testing and judging the interval matching, the sequential read speed of a solid state drive is assigned a value of Fs of 6 points, and the sequential write speed is assigned a value of Fx of 5 points. If the operator determines, based on the actual situation, that the sequential read speed is more important in the current usage scenario, then the sequential read speed weight a is set to 0.6, and the sequential write speed weight b is set to 0.4 (a+b=1, to ensure that the total weight is 1, so that the calculation result is reasonable), and these values ​​are substituted into the formula: F1=0.6*6+0.4*5=3.6+2=5.6 points.

[0049] Step S3: Analyze the random read and write speeds in the solid state drive test content, where the random read and write speeds include 4K random read speed and 4K random write speed, and the specific analysis method is as follows:

[0050] The 4K random read speed is analyzed, and the current 4K random read speed of the solid-state drive is obtained and recorded as Vd. The IOPS value is obtained at the same time, and the IOPS value is expressed as the database value corresponding to the solid-state drive. The evaluation level corresponding to the current solid-state drive is determined according to the obtained 4K random read speed and IOPS value, and the corresponding 4K random read speed assignment is obtained and recorded as Fd. Then the 4K random write speed and the corresponding IOPS value are obtained. Similarly, the analysis method of the 4K random read speed is used to determine the evaluation level of the current solid-state drive corresponding to the 4K random write speed, and the corresponding assignment is obtained and recorded as Fg. Then the obtained 4K random read speed assignment Fd and 4K random read speed assignment Fg are substituted into the formula Calculate the total value F2 of the current random read and write speed of the solid state drive.

[0051] Different evaluation levels are divided according to industry standards and the performance of similar products on the market. Level 1: 4K random read speed Vd is less than 20MB / s, and IOPS value is less than 50,000, and the assigned Fd is 1 point;

[0052] Level 2: 4K random read speed Vd is between 20MB / s (inclusive) and 35MB / s, IOPS is between 50,000 (inclusive) and 80,000, and the assigned Fd is 2 points;

[0053] Level 3: 4K random read speed Vd is between 35MB / s (inclusive) and 50MB / s, IOPS is between 80,000 (inclusive) and 120,000, and the assigned Fd is 3 points;

[0054] Level 4: 4K random read speed Vd is greater than 50MB / s, and IOPS value is greater than 120,000, and the assigned Fd value is 4 points. The 4K random write speed is classified in the same way as the 4K random read speed, and the corresponding value is assigned.

[0055] Step S4: Analyze the stability and cache capacity of the SSD test content. The stability analysis is conducted through three aspects: SSD write magnification, P / E cycle times, and temperature environment influence. The specific analysis method is as follows:

[0056] For the analysis of write amplification, which refers to the ratio of the amount of data actually written to the flash memory to the amount of data written to the SSD by the host, the write amplification of the current SSD is calculated according to the calculation formula Calculate the write amplification rate corresponding to the current solid-state drive. For example, the host write volume of the current solid-state drive is 100GB within a period of time, and the flash memory write volume is 150GB after statistics. The corresponding write amplification rate is further calculated to be 2.5 according to the formula, and the calculated write amplification rate is matched with the corresponding evaluation interval, and the corresponding write amplification rate assignment is obtained at the same time. The evaluation interval here is obtained through market research, and then the P / E cycle number of the current solid-state drive is obtained, and the evaluation level is determined according to the corresponding P / E cycle number, and the corresponding P / E cycle number assignment is determined at the same time. Then the sum of the values ​​of the write amplification rate assignment and the P / E cycle number assignment is calculated and recorded as a comprehensive assignment;

[0057] Then, the solid-state drive is placed in a high-temperature environment and a low-temperature environment for long-term read and write operations, and the data loss rate and read-write error rate corresponding to the high-temperature environment and the low-temperature environment are obtained. At the same time, the corresponding environmental rating assignment is determined according to the data loss rate and read-write error rate of different temperature environments. Specifically, the assignment corresponding to the high-temperature environment and the low-temperature environment is obtained according to the data loss rate and the read-write error rate. Then, the numerical mean of the different environmental rating assignments is calculated, and the mean is obtained as the environmental assignment, and here specifically, the assignment mean corresponding to the high-temperature environment and the low-temperature environment is calculated; the specific high-temperature setting is set according to the actual situation, but in general, the temperature setting value is 70℃-80℃, because in daily use, when the computer is running at high load for a long time, the internal hardware temperature may be close to this value. For example, in the hot summer, the ambient temperature of the solid-state drive inside the computer host without good heat dissipation conditions may reach 60-70℃. Reading and writing the solid-state drive for a long time at this temperature can simulate its performance under extreme usage conditions;

[0058] For low temperature settings, the low temperature environment may be set to -20℃--10℃. In winter in cold areas, electronic devices used outdoors, such as solid-state drives in car computers, may face such low temperature environments. Long-term reading and writing operations on solid-state drives at low temperatures of -20℃--10℃ can evaluate their stability in low temperature environments, but there are some special cases. In some polar scientific research equipment or equipment used in high-altitude low-temperature environments, the low temperatures faced by solid-state drives may be lower. For example, at the Antarctic research station, the operating environment temperature of the equipment may be as low as -40℃. For solid-state drive testing for such applications, the low temperature environment is set to -40℃.

[0059] The obtained comprehensive assignment and environmental assignment are numerically summed to obtain the stability assignment of the current solid state drive;

[0060] The analysis of cache capacity is a comprehensive analysis of the cache hit rate, read / write speed, and response time of the SSD. First, the cache hit rate, read / write speed, and response time are quantified and recorded as H, S, and R, respectively. Then, the quantified cache hit rate H, read / write speed S, and response time R are substituted into the formula The cache capacity index C corresponding to the solid-state drive is calculated. When calculating, the parameters in the above formula are substituted into their values ​​for calculation, and the units of the parameters are not substituted into the calculation. Smax is the highest read and write speed of the same type of solid-state drive, and Rmax is the longest response time of the same type of solid-state drive. They are the weight coefficients of cache hit rate, read / write speed, and response time. The weights are determined according to the actual application scenario requirements. ;

[0061] In a specific example, for example, a SSD cache hit rate H=0.8, comprehensive read / write speed S=3000, and the highest read / write speed Rmax=5000 for similar products, the current SSD response time R=0.1, the longest response time Rmax=0.2 for similar products, and the weights are determined based on the actual situation. =0.4, =0.3, =0.3, and further substitute the obtained parameters into the formula to calculate the cache capacity index C=0.65.

[0062] The obtained stability assignment and cache capacity index C are summed to obtain the comprehensive capacity value of the current solid state drive.

[0063] Step S5, perform comprehensive calculation and analysis on the obtained total sequential read / write speed value, 4K random read / write speed value and comprehensive capacity value to obtain the storage performance value of the solid state drive, and the specific comprehensive calculation method is: Substitute the obtained parameters into the formula The storage performance value P of the solid-state drive is calculated, where Q is the comprehensive capability value of the solid-state drive, and F1 and F2 are the total value of the sequential read and write speed and the value of the 4K random read and write speed respectively;

[0064] Then the obtained storage performance value P is matched with the corresponding storage performance value judgment interval, and the storage performance value judgment interval is calculated based on the data of different types of solid-state drives on the market, which are specifically classified into four levels, including advanced performance, intermediate performance, normal performance and low performance, and each level corresponds to a judgment interval value. The judgment level of the current solid-state drive is determined based on the storage performance value judgment interval, and the corresponding rating information is generated.

[0065] Specifically, through extensive testing and data collection of a large number of SSDs of different brands, models and specifications on the market, their storage performance values ​​are analyzed as follows:

[0066] Advanced performance: The storage performance value P is greater than or equal to 8.5.

[0067] Intermediate performance: The storage performance value P is between 7.0 (inclusive) and 8.5.

[0068] Normal performance: The storage performance value P is between 5.5 (inclusive) and 7.0.

[0069] Low performance: The storage performance value P is less than 5.5.

[0070] Some of the data in the above formulas are calculated by taking their numerical values, and are not substituted into parameter units for calculation. At the same time, the contents not described in detail in this specification belong to the existing technologies known to those skilled in the art.

[0071] The above embodiments are only used to illustrate the technical method of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical method of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical method of the present invention.

Claims

1. A method for testing the storage performance of a solid state drive, characterized in that: The method specifically comprises the following steps: Test and analyze from three aspects: sequential read and write speed test, random read and write speed test, stability and cache capacity test; Match the sequential read speed and sequential write speed of the solid state drive with the corresponding judgment intervals respectively, obtain the corresponding assignments, and calculate the sum of the two assignments to obtain the total assignment; Match the 4K random read speed and 4K random write speed of the solid state drive with the corresponding judgment intervals respectively, obtain the corresponding assignments, and calculate the sum of the two assignments to obtain the total assignment; Match the write amplification ratio and the number of P / E cycles with the evaluation intervals obtained through market research, obtain their corresponding values, and then add the two values ​​together to obtain a comprehensive value; Record the data loss rate and read / write error rate of the SSD in different temperature environments. According to the standards determined by market research, assign values ​​to the data loss rate and read / write error rate in different temperature environments respectively, and calculate the average of the two ratings to obtain the environmental value. Add the comprehensive value and the environmental value to obtain the stability value of the SSD. The cache hit rate, read / write speed and response time of the solid-state drive are quantified respectively, and substituted into a preset formula to calculate the cache capacity index of the solid-state drive, and the stability assignment and the cache capacity index are added to obtain the comprehensive capacity value of the solid-state drive; The storage performance value is obtained by comprehensively calculating the total assigned sequential read and write speeds, the total assigned random read and write speeds, and the comprehensive capability value, and the storage performance of the solid state drive is determined based on the storage performance value to generate rating information.

2. A method for testing the storage performance of a solid state drive according to claim 1, characterized in that: The calculation method of the total value of the sequential read and write speed is: Analyze the sequential read speed, obtain the sequential read speed corresponding to the current solid-state hard disk, record it as Vs, and generate a judgment interval according to the sequential read speeds of different solid-state hard disks and assign a value, then match the sequential read speed Vs with the judgment interval, and obtain the sequential read speed corresponding to the current solid-state hard disk, record it as Fs; Analyze the sequential write speed to obtain the sequential write speed corresponding to the current solid-state drive and record it as Vx. Similarly, the sequential read speed is analyzed and the sequential write speed of the current solid-state drive is assigned a value and recorded as Fx. Substitute the obtained assignment Fs and assignment Fx into the formula , calculate the total value F1 of the current SSD sequential read and write speed, where a and b are the weight ratios corresponding to the sequential read speed and sequential write speed, respectively, and a+b=1.

3. A method for testing the storage performance of a solid state drive according to claim 1, characterized in that: The calculation method of the total random read and write speed assignment is: The current 4K random read speed of the solid state drive is obtained, recorded as Vd, and the IOPS value is obtained at the same time, and the evaluation level corresponding to the current solid state drive and the 4K random read speed value are determined according to the obtained 4K random read speed and IOPS value, recorded as Fd; Next, obtain the 4K random write speed and the corresponding IOPS value. Similarly, the 4K random read speed analysis method is used to determine the evaluation level of the current SSD corresponding to the 4K random write speed and the value Fg. Then, substitute the obtained 4K random read speed value Fd and 4K random read speed value Fg into the formula The total assigned value F2 of the current SSD random read and write speed is calculated.

4. A method for testing the storage performance of a solid state drive according to claim 1, characterized in that: The specific calculation method of the solid state drive stability assignment is as follows: Calculate the write amplification of the current solid-state hard disk, and match the calculated write amplification with the corresponding evaluation interval to obtain the write amplification value, then obtain the P / E cycle number of the current solid-state hard disk, and determine the evaluation level and the P / E cycle number value according to the corresponding P / E cycle number, then calculate the sum of the values ​​of the write amplification value and the P / E cycle number value as the comprehensive value; Obtain the data loss rate and read / write error rate corresponding to different temperature environments of the solid state drive to determine the corresponding environmental rating assignment, then calculate the numerical mean of the different temperature environmental rating assignments, and use the obtained mean as the environmental assignment; The obtained comprehensive assignment and environmental assignment are numerically summed to obtain the stability assignment of the current solid state drive.

5. A method for testing the storage performance of a solid state drive according to claim 1, characterized in that: The specific calculation method of the SSD cache capacity index is as follows: The cache hit rate, read / write speed, and response time are quantified and recorded as H, S, and R respectively. Then, the quantized cache hit rate H, read / write speed S, and response time R are substituted into the formula The cache capacity index C corresponding to the solid-state drive is calculated, and Smax is the highest read and write speed of the same type of solid-state drive, and Rmax is the longest response time of the same type of solid-state drive. and are the weight coefficients of cache hit rate, read / write speed and response time respectively, and .

6. A method for testing the storage performance of a solid state drive according to claim 1, characterized in that: The specific calculation method of the comprehensive capability value of the solid state drive is: The obtained stability assignment and cache capacity index C are summed to obtain the comprehensive capacity value of the current solid state drive.

7. A method for testing the storage performance of a solid state drive according to claim 1, characterized in that: The specific calculation method of the solid state drive storage performance value is: Substitute the total sequential read / write speed value, 4K random read / write speed value, and comprehensive capability value into the formula The storage performance value P of the solid-state drive is calculated, where Q is the comprehensive capability value of the solid-state drive, and F1 and F2 are the total sequential read and write speed values ​​and the 4K random read and write speed values, respectively.

8. A method for testing the storage performance of a solid state drive according to claim 1, characterized in that: The specific method of generating rating information is: The obtained storage performance value P is matched with the corresponding storage performance value judgment interval, and the storage performance value judgment interval is calculated based on the data of different types of solid-state drives on the market. The judgment level of the current solid-state drive is determined based on the storage performance value judgment interval, and the corresponding rating information is generated.

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