JP3019175B2 - Improved mirrored array disk and its data input / output method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auxiliary storage device used in information processing equipment and the like, and more particularly to an auxiliary storage device which requires high-speed data input / output and high reliability of read data.

[0002]

2. Description of the Related Art In an auxiliary storage device composed of a single magnetic disk device or an optical disk device (hereinafter simply referred to as a disk device), separate data is often recorded in each disk device. When the data was destroyed, a data recovery operation such as rewriting data recorded on another medium such as a magnetic tape was required.

To improve this, redundant data is recorded on a plurality of disk devices under the name of "mirrored disk" or "array disk", and even if a part of the written data is destroyed, the data remains on the disk device. An auxiliary storage device capable of restoring corrupted data from legitimate data has been devised.

[0004] That is, in the case of a "mirrored disk", the same data is usually written to two disk devices, and at the time of reading, the data read from the two disk devices are compared, and the contents of one disk device are destroyed. If the two read data are different from each other, it is intended to improve the reliability of the data by selecting the correct data from the redundant data such as parity added in advance at the time of writing. The “mirror disk” is often realized by software.

[0005] On the other hand, an "array disk" divides write data into appropriate units as shown in FIG. 12 and simultaneously records the data on a plurality of disk devices in which the rotation of a recording medium in the disk device is synchronized. It is. When writing to the "array disk", redundant data such as ECC is recorded in each disk device.

As a result, of the plurality of disk devices,
If the contents of one disk unit are completely destroyed,
First, by identifying the disk device whose recorded content has been destroyed by redundant data such as ECC and generating the recorded content of the destroyed disk device from the recorded content of another disk device, correct data can be extracted. The “array disk” simultaneously reads and writes data from and to a plurality of disk devices, and thus has the advantage that the time required to read and write data is shorter than that of a single disk device.

[0007]

When the above-mentioned "mirrored disk" and "array disk" are combined,
"Mirrored array disk" (hereinafter referred to as "mirror array disk") as shown in FIG. 13 that can read and write the same data to two sets of "array disks" and improve the reliability of read data while reading and writing data at high speed. The term "simple mirrored array disk" may be used to distinguish it from the "improved mirrored array disk" of the present invention.

However, since the "simple type mirrored array disk" writes redundant data such as ECC into each disk device, the "simple type mirrored array disk" as a whole has more redundant data. .

Further, since exactly the same data is recorded in the disk device having the first set of “array disks” and the disk device having the second set of “array disks”, four data units are written at the time of data writing. If a burst error (continuous error) occurs simultaneously in the disk device, significant data may not be completely read from that portion.

Furthermore, if data writing to two sets of "array disks" is performed simultaneously, if the data writing is interrupted due to an instantaneous interruption of the power supply during the data writing, two sets of data are interrupted. "Array Disk"
In either case, the recorded contents during writing may be destroyed, and logically significant data may not be able to be read from either “array disk”.

In view of the above problems, the present invention eliminates the need to write a large amount of redundant data such as ECC (Error Correction Code) into two sets of "array disk" disk devices. By recording data in mutually different patterns, it is possible to reduce the amount of data lost even if a burst error occurs, and to maintain logically significant data even if the write operation is interrupted due to an instantaneous power interruption. It is an object of the present invention to provide an improved mirrored array disk capable of reading remaining data and a data input / output method therefor.

[0012]

In order to achieve the above object, an improved mirrored array disk of the present invention and a data input / output method thereof comprise a disk device such as n magnetic disk devices or optical disk devices and a control mechanism. A set of array disks, and parity of data stored in other storage elements are stored in the rightmost column and the bottom column of storage elements having n × n storage elements therein. A write data buffer unit for temporarily storing write data to be written to the disk device by changing the division manner, and one set of read data read from two sets of array disks, having the same storage elements as the write data buffer unit inside Two sets of read data buffer units that are temporarily stored separately for each array disk, and are stored in two sets of read data buffer units. Based on the comparison of the data and the parity, a validity check of the read data is performed without depending on the redundant data recording method such as the ECC, and the data is destroyed after the data write. And a control unit for controlling these units.

Further, by using the improved mirrored array disk configured as described above to write the data to the two sets of array disks sequentially instead of simultaneously, a power interruption or the like may occur during data writing. Even if the write operation is interrupted, a flag indicating which of the two sets of array disks was in the write state is recorded, so that the flag is checked after the power is restored, and the logical disk with logically significant data remains. Is a data input / output method that allows the user to select the data.

In addition, it has the same effect as such a data input / output method, and by sequentially connecting the two sets of array disks, simultaneously writing different data, it is possible to write data in two write data buffer units. In the case of continuously writing data having the above capacity, three sets of write data buffer units are provided to enable short-time writing.

Further, in such a configuration, in order to reduce the number of components while having the same effect, a write / read data buffer unit having a common set of three write data buffer units and a read data buffer unit is provided.

In addition, while having the same effect as the above-mentioned configuration having three sets of write data buffers for shortening the write time, each of the cascade-connected first and second cascade-connected devices for simplifying the internal control by the control unit. Two sets of write data buffers are provided.

Further, in order to reduce the number of components while having the same effect in such a configuration, a write / read data buffer unit having two sets of a write data buffer unit and a read data buffer unit in common is provided.

Also, using the first improved mirrored array disk, the order of transfer of write data to each disk device in the two sets of array disks is rearranged so that the same data is not transferred at the same time. It is a data input / output method capable of writing data in a shorter time than in the configuration having the above three sets of write data buffers even when writing is performed simultaneously and write data is only for one write data buffer unit. Features.

In addition, it has the same effect as the above data input / output method, and gently competes for data input from the outside to the write data buffer unit and data output timing from the write data buffer unit to the array disk. For this reason, two sets of write data buffer units are arranged in the rearrangement system of the write data transfer order.

Further, in order to reduce the number of components while having the same effect in such a configuration, a write / read data buffer unit having two sets of a write data buffer unit and a read data buffer unit in common is provided.

[0021]

According to the above arrangement, in the improved mirrored array disk and data input / output method of the present invention, data is read and written under the control of the control unit. At the time of writing, data to be written is first stored in a write data buffer having storage elements arranged in a matrix therein, and then written to two sets of array disks in different division patterns from each other.

On the other hand, when reading data, first, data is stored from two sets of array disks into two sets of read data buffers having the same configuration as the write data buffer. Each set of data from the two sets of array disks developed in a matrix on the read data buffer is checked by the check unit. If there is a difference between the data in the two sets of read data buffers, the one in which the data error is detected by the parity check is not output. Thus, E
Correct data can be output without using redundant data such as CCs. Depending on the location of the data that differs between the two sets of read data buffers and the read data buffer in which a parity error has occurred, there is an error in the read data. It is possible to specify a disk device in the array disk that has been set.

Alternatively, if the same data is simultaneously written to two sets of array disks in such a configuration, when an instantaneous power failure or the like occurs, the recorded contents of the portion being written are changed to two sets of array disks. It will be destroyed. Therefore, the same data is written to two sets of array disks with a time lag, and in the event of a power failure, a flag indicating which of the two sets of array disks was in the write state is recorded, and the flag is referred to after the power is restored. Since logically significant data always remains in one of the array disks, the data is not destroyed in both of the two sets of array disks, and significant data can always be obtained from one of the two arrays.

Alternatively, a method of writing data to one set of array disks and then writing data to another set of array disks requires a long write time. Therefore, a plurality of write data buffers, such as three sets or two sets, are provided. By writing different data to two sets of array disks at the same time, either by switching between sets of array disks or by passing data in a bucket-relay manner, the durability against power interruption during writing remains the same. In addition, data writing time can be reduced.

Alternatively, if a plurality of write data buffers and two sets of read data buffers are shared in such a configuration, the number of components can be reduced.

Alternatively, if the number of write data buffers is kept one and the data is transferred to two sets of array disks while changing the order so that the write data does not become the same, even when writing a small amount of data, Time can be reduced.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a basic type of "improved mirrored array disk" according to the first embodiment of the present invention. In this figure, “array disk 1” 1 and “array disk 2” 2 are “disk devices” having the same storage capacity.
An “array disk” consisting of n units (n is 5 in FIG. 1)
It is. The “write data buffer unit” 3 internally has n × n (5 × 5 in the embodiment of FIG. 1) storage elements in a matrix, and each storage element is divided into logically significant units. The stored write data is temporarily stored.

Next, the operation will be described.

Data writing to the “improved mirrored array disk” in FIG. 1 is performed as follows under the control of the “control unit” 7. First, data to be written is stored in the “write data buffer unit” 3. At this time, as shown in FIG. 2, the storage elements in the rightmost column and the bottom row of the “write data buffer unit” 3 store the parity of data stored in other storage elements. Next, among the data of the “write data buffer section” 3, the storage element No. 1, (n + 1), (2n + 1) ...
(In FIG. 1, 1, 6, 11, 16, 21) are the storage elements N in the first disk device of "array disk 1" 1.
o. 2, (n + 2), (2n + 2)... Are allocated to the second disk device. On the other hand, for the “array disk 2” 2, the storage element No. 1 to n
The data of Nos. 1 to 5 in FIG. 1 are stored in the first disk device in the storage element No. (N + 1) to 2n (in FIG. 1, N
o. The data of 6 to 10) is allocated to the second disk device and so on.

On the other hand, data reading is performed in the following procedure. The data read from the “array disk 1” 1 is stored in the “read data buffer unit 1” 4 and the data from the “array disk 2” 2 is stored in the “read data buffer unit 2” 5 for the time being. The “inspection unit” 6 compares the data stored in the “read data buffer unit 1” 4 and the “read data buffer unit 2” 5 and checks the validity of the read data using parity. If data is destroyed in any one of the "array disks" and the contents of the "read data buffer unit 1" 4 and the "read data buffer unit 2" 5 are different, " The data of the "read data buffer unit" is output.

Reading and writing of data as described above are performed, and two sets of "array disks" are shown at the crosses in FIG.
When there is a mismatch between the read data from 1 and 2, 2
When the parity check of the read data buffer units 4 and 5 of the set is performed and a parity error is detected in the read data buffer unit 2 5, the third disk of the array disk 2 2 It can be considered that the recorded content of the disk device has been destroyed, and the failed device can be specified. By this method, even if redundant data such as ECC is not recorded in each of the disk devices in the "array disks" 1 and 2, the disk device from which normal data could not be read can be specified.

Further, in the above read / write operation, if data mismatch between the two sets of "read data buffer units" 4, 5 in the pattern shown in FIG.
Considers that a burst error has occurred frequently on the second disk of the “array disk 1” 1, determines that this disk device is defective, and reads data from the “array disk 1” 1 It instructs to output “read data buffer unit 2” 5 ignoring “read data buffer unit 1” 4 in which read data is stored. This eliminates the effect of the burst error. It is also conceivable to replace the disk device preventively based on the determination of the disk device failure.

In the above embodiment, no consideration is given to the timing of writing data to the two sets of "array disks" 1 and 2. Two sets of "array disks"
While the same data is being written to the disk devices 1 and 2 at the same time, if the write operation is interrupted due to a power interruption or the like, the same data recording location of the two sets of “array disks” 1 and 2 becomes logical. The data is destroyed, and significant data cannot be read.

Therefore, the contents of the “write data buffer unit” 3 are described as a data input / output method according to the second embodiment.
First, the data is written to the "array disk 1" 1, and after the writing is completed, the data is written to the "array disk 2" 2. The "array disk 1" 1 and the "array disk 2"
2 At the start and end of each data write, somewhere in the "improved mirrored array disk" of the present invention,
A flag indicating whether or not the "array disks" 1 and 2 are in the write state is recorded (in such a manner that the state is maintained even when the power is turned off). In this way, even if a power interruption occurs during writing to one “array disk”, the other “array disk”
Is not writing, logically significant data remains. After the power is restored, by examining the state of the aforementioned flag, it is possible to know which of the two sets of "array disks" has not been destroyed by the power interruption,
An "array disk" in which logically significant data remains can be selected.

In the above embodiment, the reliability of the read data with respect to the interruption of the writing due to the momentary interruption of the power supply at the time of the writing is improved. However, since the data is sequentially written to the two sets of "array disks" 1 and 2, the "simple type" There is a disadvantage that the time required for writing is longer than that of the "mirrored array disk".

Therefore, as shown in the third embodiment of the present invention shown in FIG. 5, three "write data buffer units" 3 are provided, and the "write data buffer unit" 3
-1, 3-2, 3-3 are switched and used,
In the case of continuously writing 3 × 2 or more data in the “write data buffer unit”, data can be written in a short time. At this time, at the start and end of writing to the respective "array disks" 1 and 2,
A flag indicating whether the "array disks" 1 and 2 are in a write state and information indicating a write position in each disk device are "improved" (in such a manner that the state is maintained even when the power is turned off). Type mirrored array disk ". In this way, different data is simultaneously written to the two sets of “array disks” 1 and 2. Therefore, when there is an instantaneous power interruption, after the power is restored, information indicating the flag state and the write position is displayed. , Logically significant data can be extracted from the two sets of “array disks” 1 and 2.

[0038]

[Table 1] Next, as a fourth embodiment of the present invention, in the embodiment of FIG.
Although dedicated buffers are provided for the write data and the read data, the “array disks” 1, 2
Cannot write and read data at the same time, the "write data buffer unit" and the "read data buffer unit" are not used at the same time. Therefore, the number of components can be reduced by considering the "write / read data common buffer units" 8, 9, and 10 in which both buffers are common as shown in FIG. "Common buffer for write / read data"
8, 9, and 10 correspond to the data shown in FIG.
“Write data buffer section” 3-1 and 3- in the third embodiment
It functions as 2,3-3, and when reading data,
The "read data common buffer unit" 4 and 5 in the third embodiment
Function. When reading data, write
Read / read data common buffer section "
One of them is not used.

In the embodiment shown in FIG. 6, different data can be simultaneously written to the two sets of “array disks” 1 and 2, and the writing time can be reduced when writing continuous data. However, 3
A set of “write / read data common buffer unit” 8,
The control by the “control unit” 7 is complicated because the switching between 9 and 10 is used. Therefore, as shown in FIG. 7, two sets of cascaded "write data buffer units" 3-1 and 3-2 are provided as shown in FIG. If writing is performed, the same effect as that of FIG. 5 can be obtained with a small number of components. In this embodiment, in order to cope with an instantaneous power interruption during writing, etc.,
At the start and end of writing to the "array disks" 1 and 2, a flag indicating whether the "array disks" 1 and 2 are in the write state and information indicating the write position to each disk device are recorded. deep.

[0040]

[Table 2] In the embodiment of FIG. 7, as in the case of the embodiment of FIG. 6, a "write data buffer unit" and a "read data buffer unit" are shared as a sixth embodiment of the present invention.
An embodiment in which the “write / read data common buffer unit” 8 or 9 can be considered. This is shown in FIG.
"Write / read data common buffer section" 8, 9
At the time of data writing, the “write” of the fifth embodiment shown in FIG.
3-1 and 3-2.
Therefore, when reading data, the "read data"
Data common buffer units "4 and 5.

In the above-described embodiments of FIGS. 5 to 8, the writing time can be shortened when continuously writing data having a capacity of 3 × 2 or more in the “writing data buffer section”. If only 3 × 1 data buffer units have write data, the write time cannot be reduced.

Therefore, in the same configuration as the embodiment of FIG. 1, as shown in the seventh embodiment of the present invention in FIG.
If the order of transferring data to the "array disk 2" 2 is devised as shown in FIG. 9, different data can be written to two sets of "array disks" 1 and 2 at the same time. In this case, since data is simultaneously read from one set of the "write data buffer unit" 3, the write time can be reduced even when there is only 3 * 1 "write data buffer unit" write data. However, in this embodiment, since the order of writing to each disk device is disordered, the reliability of the recorded data with respect to the momentary interruption of the power supply generated at the time of writing is inferior to the embodiments of FIGS.

In the above embodiment, two sets of "array disks" 1 and one set of "write data buffer" 3 are used.
Since the data is simultaneously transmitted to the “write data buffer unit” 3, the timing for transmitting the data from the outside becomes severe.

Therefore, as in the eighth embodiment shown in FIG.
It has a set of “write data buffer units” 3-1 and 3-2, and alternately receives external data input and an “array disk”
If data is output to the "array disks" 1 and 2 as shown in FIG. 9 and data is sent to the "array disks" 1 and 2 as shown in FIG. Can be eased.

In the embodiment of FIG. 10, as in the case of the embodiment of FIG. 6, the ninth embodiment of the present invention employs "write data buffer units" 3-1 and 3-2 and "read data buffer units". An embodiment can be considered in which 4 and 5 are made common, and "write / read data common buffer units" 8 and 9 are used. This is shown in FIG.

[0046]

As described above, in the "improved mirrored array disk" of the present invention, since it is not necessary to write redundant data such as ECC to each disk device constituting two sets of "array disks", " Compared to a “simple mirrored array disk” in which a “mirrored disk” and an “array disk” are simply combined, more original data can be stored.

Also, "improved mirrored array disk"
The data stored in each disk device is different from each other, so even if a burst error occurs in multiple disk devices during writing, the data lost is smaller than that of the conventional "simple mirrored array disk". Less.

Further, some of the "improved mirrored array disks" of the present invention are designed so as not to write the same data to two sets of "array disks" at the same time. Even if the write operation is interrupted, logically significant data remains in one of the "array disks", which has the effect of improving the reliability of read data.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of an improved mirrored array disk according to one embodiment of the present invention.

FIG. 2 is a diagram showing storage contents of a write data buffer shown in FIG. 1;

FIG. 3 is a diagram showing an example of read data mismatch of the array disk shown in FIG. 1;

4 is an explanatory diagram of a burst error of read data of the array disk shown in FIG.

FIG. 5 is a configuration diagram of an improved mirrored array disk according to a third embodiment of the present invention.

FIG. 6 is a configuration diagram of an improved mirrored array disk according to a fourth embodiment of the present invention.

FIG. 7 is a configuration diagram of an improved mirrored array disk according to a fifth embodiment of the present invention.

FIG. 8 is a configuration diagram of an improved mirrored array disk according to a sixth embodiment of the present invention.

FIG. 9 is an explanatory diagram of a data transfer order in a data input / output method of an improved mirrored array disk according to a seventh embodiment of the present invention.

FIG. 10 is a configuration diagram of an improved mirrored array disk according to an eighth embodiment of the present invention.

FIG. 11 is a configuration diagram of an improved mirrored array disk according to a ninth embodiment of the present invention.

FIG. 12 is a configuration diagram of a conventional array disk.

FIG. 13 is a configuration diagram of a conventional simple mirrored array disk.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Array disk 1 2 Array disk 2 3 Write data buffer part 3-1 Write data buffer part 1 3-2 Write data buffer part 2 3-3 Write data buffer part 34 Read data buffer part 15 Read data buffer part 26 Inspection unit 7 Control unit 8 Write / read data common buffer unit 1 9 Write / read data common buffer unit 2 10 Write / read data common buffer unit 3

Claims (9)

(57) [Claims] 1. A and the write data buffer unit for storing the parity of the data to be stored in other storage elements in the memory element of the rightmost column and lowermost row has a storage element of the n × n therein, a plurality
Disk device and write data buffer
The unit that formed the parity of the rightmost column
A first array disk to be stored in the disk device and a plurality of disks.
Disk device, and is stored in the write data buffer.
The unit that formed the parity of the bottom row
Having a second array disks to be stored in the disk device, the same storage elements within the write data buffer unit, the second
Two sets of read data buffer units for temporarily storing read data read from the first and second array disks separately for each array disk, and a comparison for each data element of data stored in the two sets of read data buffer units results Oyo read out from a combination of <br/> beauty the parity check result
A checking unit that performs a data validity check and can identify as many as one disk device in the array disk in which data corruption has occurred after data writing, and a control unit that controls each unit. An improved mirrored array disk characterized in that: 2. Using the improved mirrored array disk according to claim 1, by performing write timing for the two sets of array disks sequentially instead of simultaneously, a power interruption or the like occurs during data writing. Even if the write operation is interrupted, by recording a flag indicating which of the two sets of array disks was in the write state, logically significant data remains with reference to the flag after power recovery. A data input / output method for an improved mirrored array disk, wherein one of the array disks can be selected. 3. The improved mirrored array of claim 1 wherein :
In the disk data input / output method, the write data
Data buffer section, and the three sets of write data
The buffer section operates from the first cycle to the third cycle.
Operate while shifting one cycle at a time,
New data is written to the write data buffer
In the second cycle, the written data is
Writing to the first array disk, a third cycle
Wherein the written data is stored in the second array
The control unit controls the three sets to be written to the disc.
Controlling the write data buffer unit
Improved mirrored array disk. 4. The improved mirrored array disk of claim 3, wherein said three sets of write data buffers.
Part and the two sets of data buffer parts, instead of three sets
Write / read data buffer unit for writing data
When writing, the three sets of write / read data buffers
All of the writers are the above three sets of write data buffers.
The three sets of writing /
Two sets of the read data buffer section are the two sets of data.
An improved mirrored array disk characterized by functioning as a data buffer unit . 5. The improved mirrored array according to claim 1, wherein :
In the disk, the write data buffer unit is 2
And each of the two sets of write data buffers is
The first array disk and the second array disk
Connected, the two sets of write data buffers being one
From the write data buffer of the corresponding array disk
The data that writes data to the other
An improved mirrored array disk characterized by being cascaded so as to be written to a mirror. 6. An improved mirrored array according to claim 5, wherein :
In the disk, the two sets of write data buffers
Part and two sets of data buffer parts, instead of two sets
Write / read data buffer unit for writing data
When writing, the two sets of write / read data buffers
All of the writers are the two sets of write data buffers.
The two sets of writing /
All of the read data buffer units are the two sets of data.
An improved mirrored array disk characterized by functioning as a data buffer unit . 7. A rightmost column having n × n storage elements therein.
The data stored in other storage elements is stored in the storage element at the bottom row.
Write data buffer for storing parity and multiple
Each disk unit has a predetermined unit.
The first array disk to remember and multiple disk devices
And the predetermined unit is the first array disk.
Second array stored in each disk device at different times
Write the same data to the disk and the write data buffer
Memory element, from the first and second array disks
Read data to be read separately for each array disk
Two sets of read data buffers to be temporarily stored, and the two sets
Of data stored in the read data buffer section
Combination of comparison result and parity check result for each element
Check the validity of the read data from the matching
In the array disk where data corruption occurred after writing
Can be specified as long as there is only one disk unit.
Inspection unit, and a control unit for controlling each of the units.
An improved mirrored array disk characterized by the following. 8. The data input / output method for an improved mirrored array disk according to claim 7 , wherein said write data
Data buffer unit, two sets of data buffers
While writing data to one of the
And reads the read data from the first and second arrays.
An improved mirrored array disk characterized by writing to a disk. 9. The improved mirrored array disk of claim 8, wherein said two sets of write data buffers.
Part and two sets of data buffer parts, instead of two sets
Write / read data buffer unit for writing data
When writing, the two sets of write / read data buffers
All of the writers are the two sets of write data buffers.
The two sets of writing /
All of the read data buffer units are the two sets of data.
An improved mirrored array disk characterized by functioning as a data buffer unit .