JP2018169980A - Storage device, control method thereof, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a storage device configured to extend service life of the whole of a storage system including multiple SSDs.SOLUTION: A storage device includes a life estimation unit and a data exchange unit. The life estimation unit estimates service life of SSDs on the basis of information on an alternative sector in each of the SSDs and data write cycle for each of the SSDs. The data exchange unit exchanges data stored in a first SSD of the SSDs having an estimated life value smaller than a predetermined value, for data stored in a second SSD of the SSDs different from the first SSD. The data exchange unit calculates life reduction value in each of the SSDs when the data stored in the first SSD is stored in each of SSDs excluding the first SSD, and selects the second SSD on the basis of the life reduction value.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a storage apparatus, a storage apparatus control method, and a program. In particular, the present invention relates to a storage apparatus having a plurality of storage media, a storage apparatus control method, and a program.

  In recent years, a storage medium called SSD (Solid State Drive) has been widely used (Patent Documents 1 to 4).

  Patent Document 1 discloses a technique for monitoring the number of times of writing in each of a plurality of SSDs, and performing data swapping when the number of times of writing is extremely biased between SSDs, and leveling the number of times of writing.

  Patent Document 2 discloses a technique for saving a part of data to a spare disk (spare storage device) when the number of writes to the SSD is greater than a predetermined number.

  Patent Document 3 considers whether the SSD characteristics are SLC (Single-Level-Cell) or MLC (Multi-Level-Cell) when allocating a write area to the SSD. A technique for allocating MLC and allocating MLC when the writing frequency is low is disclosed.

  Patent Document 4 discloses a technique for leveling deterioration between a plurality of storage media. In Patent Document 4, a second logical storage area that is assigned a storage device different from the storage device assigned to the first logical storage area and has an estimated data amount smaller than the estimated data of the first logical storage area is selected. It is described that the first data stored in the logical storage area is moved to the second logical storage area.

  Patent Document 5 discloses a technology related to CompactFlash (registered trademark). In Patent Document 5, when the number of alternative sectors exceeds a threshold, product sales data is stored in a memory, and in response to the end of registration of product sales data, a plurality of product sales data stored in the memory are collectively stored in a compact flash ( Disclosure of technology for writing on a registered trademark card.

Japanese Patent No. 5242264 JP 2010-55247 A Japanese Patent No. 5192352 International Publication No. 2014/141411 JP 2006-155532 A

  Each disclosure of the above prior art document is incorporated herein by reference. The following analysis was made by the present inventors.

  The number of writes to the SSD affects the life of the SSD. Therefore, as described above, there are various techniques related to SSD writing. However, the life of the SSD is not determined depending only on the number of times of writing, and even if data writing to the SSD is suppressed, the life of the SSD cannot be guaranteed.

  The reason is that the actual SSD reaches the end of its life because the depletion of alternative sectors is considered as the main factor. That is, the number of times of writing to the SSD is one of methods for estimating the life of the SSD, and is insufficient unless the existence of the alternative sector is taken into consideration. For example, Patent Document 1 does not mention observing the usage amount of alternative sectors.

  The SSD internal control circuit recovers the state by switching to the alternative sector when the reading / writing of the SSD fails. An SSD read / write failure may occur probabilistically depending on the number of writes, but the frequency of occurrence varies depending on the surrounding environment and the characteristics of the SSD element. For example, when the ambient temperature is high, there is a high possibility that a write error will occur. It should also be considered that the error tolerance differs depending on whether the characteristics of the individual NAND flash are SLC or MLC.

  Patent Document 3 discloses a method of selecting whether to assign a region with a high rewrite frequency or a region with a low rewrite frequency according to the characteristics of the storage element (depending on whether it is SLC or MLC). However, even in the technology disclosed in this document, the actual amount of use of alternative sectors has not been verified. Therefore, even if the number of times of writing is small, there is a high possibility that the alternative sector will be consumed at the time of writing if there is an SSD with a large usage amount of the alternative sector. As a result, there is a possibility that the SSD life may be shortened by writing at the time of data swap between SSDs.

  An object of the present invention is to provide a storage apparatus, a storage apparatus control method, and a program that extend the life of the entire storage system including a plurality of SSDs.

  According to the first aspect of the present invention, the lifetime value of each SSD is estimated based on the information regarding the alternative sector in each of a plurality of SSDs (Solid State Drives) and the number of times data is written to each of the plurality of SSDs. A life estimation unit, data stored in a first SSD whose estimated life value is smaller than a predetermined value among the plurality of SSDs, and a first one of the plurality of SSDs different from the first SSD. A data exchange unit for exchanging data stored in the SSD of the second SSD, wherein the data exchange unit converts the data stored in the first SSD to the first of the plurality of SSDs. A storage apparatus is provided that calculates a life shortening amount in each SSD when stored in each of the SSDs excluding the SSD, and selects the second SSD based on the life shortening amount. It is.

  According to the second aspect of the present invention, the step of estimating the lifetime value of each SSD based on the information regarding the alternative sector in each of a plurality of SSDs (Solid State Drives) and the number of times data is written to each of the plurality of SSDs. And the data stored in the first SSD having the estimated lifetime value smaller than a predetermined value among the plurality of SSDs, and the second SSD different from the first SSD among the plurality of SSDs. And exchanging data stored in the first SSD of the plurality of SSDs except for the first SSD. And calculating a life shortening amount in each SSD when stored in each of the storage devices, and selecting the second SSD based on the life shortening amount. Your method is provided.

According to a third aspect of the present invention, there is provided a program to be executed by a computer installed in a storage apparatus, wherein information relating to an alternative sector in each of a plurality of SSDs (Solid State Drives) and data for each of the plurality of SSDs are stored. A process of estimating the life value of each SSD based on the number of times of writing; data stored in a first SSD having the estimated life value smaller than a predetermined value among the plurality of SSDs; Processing for exchanging data stored in a second SSD different from the first SSD in the SSD is executed by the computer, and the processing for exchanging the data is stored in the first SSD. The life reduction amount of each SSD when the obtained data is stored in each of the plurality of SSDs excluding the first SSD is calculated. While, selecting the second of the SSD based on the lifetime-reducing amount, a program is provided.
This program can be recorded on a computer-readable storage medium. The storage medium may be non-transient such as a semiconductor memory, a hard disk, a magnetic recording medium, an optical recording medium, or the like. The present invention can also be embodied as a computer program product.

  According to each aspect of the present invention, a storage apparatus, a storage apparatus control method, and a program that contribute to extending the life of the entire storage system including a plurality of SSDs are provided.

It is a figure for demonstrating the outline | summary of one Embodiment. It is a figure which shows an example of schematic structure of the storage apparatus which concerns on 1st Embodiment. It is a figure which shows an example of a process structure of the device controller which concerns on 1st Embodiment. It is a figure for demonstrating operation | movement of the storage apparatus which concerns on 1st Embodiment. It is a figure which shows another example of schematic structure of the storage apparatus which concerns on 1st Embodiment.

  First, an outline of one embodiment will be described. Note that the reference numerals of the drawings attached to the outline are attached to the respective elements for convenience as an example for facilitating understanding, and the description of the outline is not intended to be any limitation. In addition, the connection lines between the blocks in each drawing include both bidirectional and unidirectional directions. The unidirectional arrow schematically shows the main signal (data) flow and does not exclude bidirectionality.

  The storage apparatus 10 according to an embodiment includes a life estimation unit 201 and a data exchange unit 202 (see FIG. 1). The life estimation unit 201 estimates the life value of each SSD based on information on alternative sectors in each of a plurality of SSDs (Solid State Drives) and the number of times data is written to each of the plurality of SSDs. The data exchange unit 202 includes data stored in a first SSD whose estimated life value is smaller than a predetermined value among a plurality of SSDs, and a second SSD different from the first SSD among the plurality of SSDs. Exchange data stored in Further, the data exchanging unit 202 calculates the life shortening amount in each SSD when the data stored in the first SSD is stored in each of the SSDs excluding the first SSD among the plurality of SSDs. The second SSD is selected based on the shortening amount.

  As described above, the life of the SSD is considered to be due to the exhaustion of the alternative sector. However, in order to extend the life of the SSD (extend the life of the SSD), it is also necessary to allocate to an area where the number of writings is small. Therefore, the storage apparatus 10 observes both information relating to the alternative sector of the SSD (for example, the usage amount of the alternative sector) and the number of times of writing, and predicts a decrease in the life of the SSD from the calculation result using the information. When the storage device 10 determines that the life of a specific SSD is short, the storage device 10 performs data swap with another SSD having a long life. As a result, the life of the entire storage system equipped with the SSD is extended. In addition, since the life of the entire storage system is extended, the reliability of the entire system can be improved.

  Hereinafter, specific embodiments will be described in more detail with reference to the drawings. In addition, in each embodiment, the same code | symbol is attached | subjected to the same component and the description is abbreviate | omitted.

[First Embodiment]
The first embodiment will be described in more detail with reference to the drawings.

  FIG. 2 is a diagram illustrating an example of a schematic configuration of the storage apparatus 1 according to the first embodiment. Referring to FIG. 2, the storage apparatus 1 includes a storage controller 11 and a plurality of SSDs 12-15.

  The storage controller 11 is means for controlling the entire storage apparatus 1. Each of the SSDs 12 to 15 is a storage device that holds data. The storage controller 11 includes a device controller 111 that controls the SSDs 12 to 15 (the device controller 111 is mounted).

  The device controller 111 is connected to the SSDs 12 to 15 via device interfaces 112 to 115 corresponding to the respective SSDs. The storage controller 11 also includes write number counters 1121 to 1151 corresponding to the device interfaces 112 to 115 and the SSDs 12 to 15.

  The write count counters 1121-1115 are means for monitoring the number of writes to the corresponding SSDs 12-15. More specifically, the write count counters 1121 to 1151 are installed corresponding to the plurality of SSDs 12 to 15, respectively, and measure the cumulative number of times of writing data to the corresponding SSD.

  In addition, alternative sectors 121 to 151 are mounted on the SSDs 12 to 15, respectively. The alternative sectors 121 to 151 are consumed as necessary. In FIG. 2, the grayed out areas are the alternative sector use areas 1211 to 1511, which are consumed by the alternative sectors.

  The storage areas of the SSDs 12 to 15 are configured by RAID (Redundant Arrays of Inexpensive Disks) between the SSDs 12 to 15. That is, the storage apparatus 1 has a function of distributing and storing data and redundant codes in order to configure a RAID (for configuring a RAID) using a plurality of SSDs 12 to 15. The striping group 21 is composed of data areas 212 to 215.

  In FIG. 2, the host connected to the storage apparatus 1 and the interface with the host are not shown.

  FIG. 3 is a diagram illustrating an example of a processing configuration of the device controller 111. Referring to FIG. 3, the device controller 111 includes a life estimation unit 101 and a data exchange unit 102. The device controller 111 can be realized by a program that causes a computer installed in the storage apparatus 1 to execute processing modules including the life estimation unit 101 and the data exchange unit 102.

  The life estimation unit 101 is a means for estimating the life value of each SSD based on the information regarding the alternative sector in each of the plurality of SSDs 12 to 15 and the number of times data is written to each of the plurality of SSDs 12 to 15. The life estimation unit 101 creates a lifespan parameter for each SSD based on the combination of the consumption of alternative sectors and the number of writes in each SSD.

  The data exchange unit 102 includes data stored in a first SSD whose estimated life value (lifetime parameter) is smaller than a predetermined value among the plurality of SSDs 12 to 15, and the first of the plurality of SSDs 12 to 15. This is means for exchanging data stored in a second SSD different from the SSD. At the time of data exchange, the data exchange unit 102 calculates the life reduction amount in each SSD when the data stored in the first SSD is stored in each of the SSDs 12 to 15 excluding the first SSD. While calculating, the second SSD is selected based on the calculated life reduction amount.

  That is, the data exchanging unit 102 swaps the writing process to the SSD whose life expectancy is long from the SSD whose lifetime is expected to deteriorate (data is moved between the SSDs). By such processing of the device controller 111, the expected lifetime between SSDs is leveled, and the lifetime of the entire storage system can be extended.

  The data exchanging unit 102 performs data swap for each RAID striping. More specifically, the data exchange unit 102 uses the data exchange unit when exchanging data between the first and second SSDs as described above as a reference for the size of the striping group constituting the RAID. For example, the data exchange unit 102 exchanges data between SSDs in units of blocks, and does not exchange data smaller than one block between SSDs. For example, in the example of FIG. 2, data swap (data movement between SSDs) is performed between the data areas 212 to 215 belonging to the same striping group 21.

  In addition, when exchanging data between SSDs, the data exchange unit 102 rewrites information constituting the RAID. Specifically, the data exchange unit 102 updates information indicating data and an SSD of the storage destination among the information that links the plurality of SSDs 12 to 15 at the time of data movement between the SSDs. As a result, the movement of data between SSDs is hidden from the host. In other words, the movement of data between SSDs is hidden by the storage controller 11 (device controller 111) side, and the host is not aware of it.

The life estimation unit 101 creates a life parameter for each SSD according to the following equation (1).
Lt_SSD _x = α-β * Wcount _x -γ * Ssector _x * CapAll / (SsecCap * Wcount _x ) (1)

In equation (1), the suffix x indicates the SSD number (identifier). Lt_SSD _x indicates an estimated value of the life of each SSD. Wcount _x indicates the number of writes to each SSD. Sector _x indicates the usage amount of the alternative sector. In other words, Sector _x is equivalent to the number of sectors in which an error (substitution) has occurred in SSD. CapAll indicates the total storage capacity of the SSD excluding the alternative sector. SsecCap indicates the total capacity of alternative sectors of each SSD. α, β, and γ indicate parameters for each type of SSD. More specifically, α is a reference value of the SSD life, β is a deterioration coefficient depending on the number of times of writing, and γ is a life shortening coefficient in the alternative sector usage amount.

  In the above equation (1), the second term on the right side indicates the amount of decrease in the lifetime due to the number of writings. The third term on the right side shows that the life of each SSD is shortened when the usage amount of the alternative sector is larger than the total capacity of the alternative sector and when the total capacity of the alternative sector is smaller than the total storage capacity. Indicates that

The lifetime estimation unit 101 calculates an estimated value (lifetime parameter) of the lifetime for each SSD using the above equation (1). Of the parameters necessary for the calculation of the above formula (1), Wcount _x is obtained by the write count counters 1121-1115. In addition, Sector _x is information used by the device controller 111 itself (life estimation unit 101 itself) since it is the usage amount of the alternative sector. Other information, for example, CapAll, SsecCap, α, β, and γ are values determined by the specifications of each SSD. Therefore, these pieces of information may be input to the device controller 111 in advance.

The data exchange unit 102 performs threshold processing on the estimated life value Lt_SSD _x calculated by the life estimation unit 101, and performs data swap if the estimated value is smaller than a predetermined threshold value. Alternatively, the data exchange unit 102 may determine that the life expectancy is short when the estimated lifetime value is smaller than that of other SSDs, and avoid the deterioration of the lifetime by performing data swap.

  Whether or not to perform data swap by the data exchange unit 102 is determined at a timing when data larger than a predetermined size is written to any one of the plurality of SSDs. For example, when data larger than one block is written to the SSD, it is determined whether or not the data swap is necessary. Alternatively, when data larger than one block is written to the SSD, the life estimation unit 101 may estimate the life of each SSD, and then the data exchange unit 102 may determine whether or not to perform data swap.

The data exchange unit 102 obtains a life change difference from the area size to be swapped. That is, the data exchange unit 102 predicts the life of each SSD after data swap. When the predicted life after swap is expressed as Lt_SSD _x ′, the predicted life Lt_SSD _x ′ is calculated by the following equation (2).

Lt_SSD _x '= α-β * (Wcount _x + SWsize _x / Block) -γ * Ssector _x * CapAll * (Wcount _x + SWsize _x / Block) / (SsecCap * Wcount _x ^ 2)) (2)

In the above formula (2), SWsize _x indicates the size in the region with high update frequency in the SSD region. SWsize _x is the size of data to be replaced by data swap. Block indicates a write update unit for each SSD type. Block is the minimum rewrite unit of SSD. That is, the data exchange unit 102 uses the size (Block) of the striping group constituting the RAID as a reference for the data exchange unit when exchanging data between SSDs. In other words, data is exchanged in units of blocks, and data having a size smaller than one block is not exchanged. Note that the number of rewrites at the time of data swap can be obtained by calculating SWsize _x / Block.

Here, the consumption amount Sector _x of the alternative sector is also predicted to increase due to the rewriting process. The increase amount is shown in the form of an increase amount of the rewrite count Wcount _x . Assuming that the number of rewrites after data swap is Wcount _x ′, the number of rewrites is obtained by the following equation (3).
Wcount _x '= Wcount _x + SWsize _x / Block (3)

Since the increase amount of the alternative sector is expressed as a ratio to the original number of rewrites, the increase ratio δ is obtained by the following equation (4).
δ = Wcount _x '/ Wcount _x = (Wcount _x + SWsize _x / Block) / Wcount _x (4)

When the number of rewrites of the second term on the right side in equation (1) is replaced with Wcount _x ′ in equation (3), and the third term on the right side in equation (1) is multiplied by the increase ratio δ in equation (4), Equation (2) is obtained. However, strictly speaking, it is preferable to replace the denominator of the third term on the right side by the number of rewrites Wcount _x ′. However, since the consumption of the alternative sector is estimated to be small, the denominator of the third term on the right side in Equation (1) is It is immutable.

  When execution of the data swap is determined, the data exchange unit 102 calculates the amount of shortening of the lifetime of each SSD that is a candidate for the data movement destination using the equations (1) and (2).

Here, a small reduction in the life of the SSD is equivalent to a long life of the original SSD and a small change in the life. Therefore, the data exchange unit 102 calculates a life shortening amount by subtracting the life span Lt_SSD _x ′ after the data swap from the original life span estimated value Lt_SSD _x as shown in the following equation (5).

Lt_SSD _x -Lt_SSD _x '
= (β + γ * Ssector _x * CapAll / (SsecCap * Wcount _x ^ 2)) * SWsize _x / Block) (5)

  Since the value of the above formula (5) is the shortening amount of the lifetime, the data exchange unit selects the SSD having the smallest value as the swap target.

  Next, the operation of the storage apparatus 1 according to the first embodiment will be described with reference to FIG. In FIG. 4, it is assumed that the capacity of the gray area is consumed in the alternative sectors 121 to 151 of the SSDs 12 to 15 (the size of the alternative sector usage areas 1211 to 1511 is used for the alternative sectors 121 to 151). Have been). Further, the number of writes to the SSDs 12 to 15 (count values held by the write number counters 1121 to 1151) is N1, N2, N3, and N4.

  The magnitude relationship of the number of times of writing is as shown in the following formula (6).

N4> N3> N2> N1 (6)

  The device controller 111 calculates the expected life of each SSD based on the size of the alternative sector use area 1211 to 1511 of each SSD and the value of each write count counter 1121 to 1151. Specifically, the device controller 111 applies the formula (1) to each of the SSDs 12 to 15 and calculates the predicted life of each SSD by the following formulas (7) to (10).

Lt_SSD ₁₂ = α-β * N1-γ * Ssector ₁₂ * CapAll / (SsecCap * N1) (7)
Lt_SSD ₁₃ = α-β * N2-γ * Ssector ₁₃ * CapAll / (SsecCap * N2) (8)
Lt_SSD ₁₄ = α-β * N3-γ * Ssector ₁₄ * CapAll / (SsecCap * N3) (9)
Lt_SSD ₁₅ = α-β * N4-γ * Ssector ₁₅ * CapAll / (SsecCap * N4) (10)

  If SSDs are all the same type, α, β, and γ are fixed values. In the above formulas (7) to (10), a code indicating each SSD is a suffix x.

When the predicted life value Lt_SSD 12 of the SSD ₁₂ is the smallest and the predicted life value is smaller than a predetermined threshold as a result of the calculations according to the above (7) to (10), the device controller 111 stores the data stored in the SSD 12 Determine the swap.

  The device controller 111 obtains an SSD as a counterpart when swapping the data of the SSD 12 by the following equations (11) to (13).

Lt_SSD ₁₃ -Lt_SSD ₁₃ '
= (β + γ * Ssector ₁₃ * CapAll / (SsecCap * N2 ^ 2)) * SWsize _x / Block) (11)
Lt_SSD ₁₄ -Lt_SSD ₁₄ '
= (β + γ * Ssector ₁₄ * CapAll / (SsecCap * N3 ^ 2)) * SWsize _x / Block) (12)
Lt_SSD ₁₅ -Lt_SSD ₁₅ '
= (β + γ * Ssector ₁₅ * CapAll / (SsecCap * N4 ^ 2)) * SWsize _x / Block) (13)

  When the equations (11) to (13) are confirmed, the amount of reduction in the life of the SSD after the data swap increases as the consumption amount of the alternative sector increases. Specifically, the life shortening amount of the SSD 13 calculated by the equation (11) is the smallest, and the life shortening amount of the SSD 14 calculated by the equation (12) is the largest.

  The device controller 111 selects the SSD having the smallest SSD life reduction amount as the data swap partner. In the above example, the SSD 13 is a data swap partner.

  As described above, the device controller 111 selects an SSD that is a data swap partner (data transfer destination) that consumes less alternative sectors in addition to the number of writes. In the example of FIG. 4, when the device controller 111 determines that the life of the SSD 12 is short, the device controller 111 performs data swap between the SSD 12 and the SSD 13.

  The configuration and operation of the storage apparatus 1 described in the above embodiment are merely examples, and are not intended to limit the system configuration. For example, each SSD may not constitute a RAID, and the data areas 212 to 215 in FIG. 4 may be independent from each other (see FIG. 5). Even in such a case, data swap is possible if the unit of writing in the data area is determined.

  As described above, the storage apparatus 1 according to the first embodiment predicts the actual life span of the SSD more accurately by monitoring the usage amount of the alternative sector of the SSD. This is because the depletion of the alternative sector affects the life of the SSD itself, so that the state of the SSD can be confirmed directly from the observation of the number of times of writing.

  From the above description, the industrial applicability of the present invention is clear, but the present invention can be suitably applied to a disk array device including a plurality of storage media. By applying it to a disk array device, the life of the device can be extended. In other words, the life span of a single SSD tends to increase due to wear leveling inside the SSD and the capacity of alternative sectors, etc. If the life extension effect of the entire device is added to this, the life span of the SSD can be reduced to the device life. It becomes possible to extend, and it becomes possible to reduce the exchange of SSD.

A part or all of the above embodiments can be described as in the following supplementary notes, but is not limited thereto.
[Appendix 1]
This is the same as the storage apparatus according to the first aspect described above.
[Appendix 2]
The life estimation unit is
The storage device according to appendix 1, wherein the information regarding the alternative sector uses a total capacity of the alternative sector and a usage amount of the alternative sector.
[Appendix 3]
The data exchange unit
Determining whether to exchange data between the first SSD and the second SSD when data larger than a predetermined size is written to any one of the plurality of SSDs; The storage device according to appendix 1 or 2.
[Appendix 4]
The data exchange unit
The storage apparatus according to any one of appendices 1 to 3, wherein an SSD having the smallest life shortening amount is selected as the second SSD among the SDDs for which the life shortening amount has been calculated.
[Appendix 5]
The storage apparatus according to any one of appendices 1 to 4, comprising a function of distributing and storing data and redundant codes so as to form a RAID (Redundant Array of Inexpensive Disks) using the plurality of SSDs.
[Appendix 6]
The storage device according to appendix 5, wherein the data exchanging unit is based on the size of the striping group that constitutes the RAID as a data exchanging unit when exchanging data between the first and second SSDs.
[Appendix 7]
The data exchange unit
The storage device according to appendix 6, wherein information constituting the RAID is rewritten when data is exchanged between the first and second SSDs.
[Appendix 8]
The storage apparatus according to any one of appendices 1 to 7, further comprising a plurality of write count counters that correspond to each of the plurality of SSDs and that measure a cumulative write count of data to the corresponding SSD.
[Appendix 9]
This is the same as the storage apparatus control method according to the second aspect described above.
[Appendix 10]
It is as the program which concerns on the above-mentioned 3rd viewpoint.
[Appendix 11]
A storage device incorporating a plurality of SSDs,
A means for confirming the total capacity of the alternative sector in the SSD and the capacity of the used alternative sector, and a function of measuring the cumulative number of writes for each SSD;
Predicting the life of each SSD based on the total capacity of the alternative sectors for each SSD, the capacity of used alternative sectors, and the cumulative number of writes;
And,
For each SSD, when a data unit of a certain capacity defined in the storage device is written, the amount of shortening of the life of each SSD is predicted,
A function of selecting the SSD having the smallest amount of shortened predicted life after writing,
If the SSD with the shortest predicted life becomes shorter than the threshold determined in the storage device, the SSD data with the shortest predicted life and the SSD data with the shortest predicted life reduction amount are obtained. A storage device having a replacement function.
[Appendix 12]
A storage device incorporating a plurality of SSDs,
Means for confirming the total capacity of the alternative sectors in the SSD and the capacity of the used alternative sectors;
In addition, it has a function of measuring the cumulative number of writes for each SSD,
Predicting the life of each SSD based on the total capacity of the alternative sectors for each SSD, the capacity of used alternative sectors, and the cumulative number of writes;
And,
For each SSD, when a data unit of a certain capacity defined in the storage device is written, the life change of each SSD is predicted,
A function of selecting the SSD having the smallest amount of shortened predicted life after writing,
If the SSD with the shortest predicted life becomes shorter than the threshold determined in the storage device, the SSD data with the shortest predicted life and the SSD data with the shortest predicted life reduction amount are obtained. A storage control system characterized by having a function of replacing.
[Appendix 13]
The storage device described in the appendix 11,
It has the function of a disk array device that performs redundant recording called RAID,
The disk array device according to claim 11, wherein when the data is replaced as described in Appendix 11, the data replacement unit is based on the size of the striping group constituting the RAID.
[Appendix 14]
The disk array device according to appendix 13, wherein
When the data is replaced, by simultaneously rewriting the information constituting the RAID,
A disk array device that performs control so that there is no change in a RAID reconstruction procedure before and after data replacement.
Note that the form of Supplementary Note 9 and the form of Supplementary Note 10 can be developed into the form of Supplementary Note 2 to the form of Supplementary Note 8, similarly to the form of Supplementary Note 1.

  Each disclosure of the cited patent documents and the like cited above is incorporated herein by reference. Within the scope of the entire disclosure (including claims) of the present invention, the embodiments and examples can be changed and adjusted based on the basic technical concept. In addition, various combinations or selections of various disclosed elements (including each element in each claim, each element in each embodiment or example, each element in each drawing, etc.) within the scope of the entire disclosure of the present invention. Is possible. That is, the present invention of course includes various variations and modifications that could be made by those skilled in the art according to the entire disclosure including the claims and the technical idea. In particular, with respect to the numerical ranges described in this document, any numerical value or small range included in the range should be construed as being specifically described even if there is no specific description.

1, 10 Storage device 11 Storage controller 12-15 SSD
21 Striping group 101, 201 Life estimation unit 102, 202 Data exchange unit 111 Device controller 112-115 Device interface 121-151 Alternate sector 212-215 Data area 1121-1151 Write frequency counter 1211-1511 Alternate sector used area

Claims (10)

A life estimation unit that estimates a life value of each SSD based on information on alternative sectors in each of a plurality of SSDs (Solid State Drives) and the number of times data is written to each of the plurality of SSDs;
Among the plurality of SSDs, the data stored in the first SSD whose estimated lifetime value is smaller than a predetermined value and the second SSD among the plurality of SSDs different from the first SSD A data exchange unit for exchanging data with
With
The data exchange unit calculates a life reduction amount in each SSD when the data stored in the first SSD is stored in each of the plurality of SSDs excluding the first SSD, and A storage apparatus that selects the second SSD based on the life shortening amount. The life estimation unit is
The storage apparatus according to claim 1, wherein the information regarding the alternative sector uses a total capacity of the alternative sector and a usage amount of the alternative sector. The data exchange unit
Determining whether to exchange data between the first SSD and the second SSD when data larger than a predetermined size is written to any one of the plurality of SSDs; The storage apparatus according to claim 1 or 2. The data exchange unit
The storage apparatus according to any one of claims 1 to 3, wherein an SSD having the smallest life shortening amount is selected as the second SSD among the SDDs for which the life shortening amount has been calculated.   The storage apparatus according to any one of claims 1 to 4, further comprising a function of distributing and storing data and redundant codes so as to form a RAID (Redundant Array of Inexpensive Disks) using the plurality of SSDs.   6. The storage apparatus according to claim 5, wherein the data exchange unit uses a size of a striping group constituting the RAID as a reference for a data exchange unit when exchanging data between the first and second SSDs. The data exchange unit
The storage apparatus according to claim 6, wherein when the data is exchanged between the first and second SSDs, information constituting the RAID is rewritten.   The storage apparatus according to claim 1, further comprising a plurality of write count counters corresponding to each of the plurality of SSDs and measuring a cumulative write count of data with respect to the corresponding SSD. Estimating a life value of each SSD based on information on alternative sectors in each of a plurality of SSDs (Solid State Drives) and the number of times data is written to each of the plurality of SSDs;
Among the plurality of SSDs, the data stored in the first SSD whose estimated lifetime value is smaller than a predetermined value and the second SSD among the plurality of SSDs different from the first SSD Exchanging data with
Including
Exchanging the data comprises:
When the data stored in the first SSD is stored in each of the SSDs excluding the first SSD among the plurality of SSDs, a life reduction amount in each SSD is calculated, and based on the life reduction amount A storage apparatus control method for selecting the second SSD. A program to be executed by a computer installed in a storage device,
A process of estimating a life value of each SSD based on information on alternative sectors in each of a plurality of SSDs (Solid State Drives) and the number of times data is written to each of the plurality of SSDs;
Among the plurality of SSDs, the data stored in the first SSD whose estimated lifetime value is smaller than a predetermined value and the second SSD among the plurality of SSDs different from the first SSD The process of exchanging data with
To the computer,
The process of exchanging the data includes
When the data stored in the first SSD is stored in each of the SSDs excluding the first SSD among the plurality of SSDs, a life reduction amount in each SSD is calculated, and based on the life reduction amount A program for selecting the second SSD.

Images