JPH01320524A - Data memory device - Google Patents

Abstract

PURPOSE:To improve reliability by providing a record storage area in a storage means in duplicate, storing new data in the record storage area at a nonuse side by the storage means, and changing the display of a memory selection table by a table control part. CONSTITUTION:In the case of reading out a record, a record number is outputted to the output of a latch 37, and the memory selection table 31 outputs a signal representing which memory, a memory 0 or a memory 1 is effective by the record to be read. The output of the latch 37 is held at an inactive state, the signal of a memory 30 is set at a readout state. Also, an exclusive OR gate 32 is set at the inactive state. To the output of the gate 32, the output of the table 31 is inputted, and that of the gate 32 becomes equal to that of the table 31, and it is inputted to the switching signal of the memory, therefore, the memory shown as effective by the table 31 out of the memory 30 is selected. In such a way, it is possible to prevent preceding data from being destroyed even when data to be updated is interrupted on the middle way.

Description

[Detailed Description of the Invention] [Summary] It relates to a data storage device, in particular, a storage means that uses data composed of multiple words as a unit of data update, stores the data as a physical record, and stores the physical record number and logical record. Regarding a data storage device that has a record number conversion table that associates numbers with record numbers, even if a failure occurs during data update and the data update is interrupted, problems such as system down will not occur. In a data storage device that has a storage means for storing data composed of multiple words as a record and uses data composed of multiple words as a unit of data update, the storage means has a double record storage area. In addition to providing storage means for storing new data in the record storage area on the side that is not currently in use when updating data, the memory also displays which side of the record storage area is currently valid. A selection table is provided, and a table control section changes the display of the memory selection table after confirming that the new data has been properly stored in the record.

[Industrial application field]

The present invention relates to a data storage device, and particularly to a storage means that uses data composed of multiple words as a unit of data update, stores the data as a physical record, and record number conversion that associates the physical record number with a logical record number. The present invention relates to a data storage device having a table.

[Conventional technology]

Generally, when an external storage device such as a magnetic disk device is shared by multiple host computers, the control device for this external storage device will control the external storage device when one device is using the external storage device. Exclusive control is required to prevent the device from being used. Therefore, it is necessary to store all the data necessary for this exclusive control in one storage device, and in this data storage device,
Reading and updating of data is performed in units of records consisting of data of multiple words regarding one device of the external storage device.

(Problems to be Solved by the Invention) By the way, in the above-described conventional data storage device, there are cases where the data update is interrupted for some reason during the data update. Then, there is a problem that neither the data before the update nor the data being updated can be used, and there is a possibility that the system will go down.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a data recording device that does not cause problems such as system down even if a failure occurs during data updating and the data updating is interrupted.

[Means to solve the problem]

In the present invention, means for solving the above problems are as follows:
As shown in FIG. 1, in a data storage device that has a storage means for storing data made up of multiple words as a record and uses data made up of multiple words as a unit of data update, the storage means 1 has two A record storage area is provided in the record storage area, and a storage means 2 is provided for storing new data in the record storage area that is currently not in use when data is updated, and which side of the record storage area is currently valid. A memory selection table 3 is provided to display whether or not the new data is stored in the record, and a table control section 4 is provided to change the display of the memory selection table after confirming that the new data has been properly stored in the record.

(Operation) According to the present invention, the storage means is provided with dual record storage areas, and when updating data, the storage means stores new data in the record storage area that is currently not being used. , the table control unit changes the display of the memory selection table after confirming that the above new data has been successfully stored in the record, so even if the data to be updated is interrupted midway, the data immediately preceding the record will not be destroyed. .

〔Example〕

Embodiments of the data storage device according to the present invention will be described below based on the drawings.

FIGS. 2 to 6 show a first diagram of a data storage device according to the present invention.
This is an example of the following. In this embodiment, the data storage device is applied to a system as shown in FIG.

This system is applied to a semiconductor disk as an external storage device, uses a semiconductor memory as a storage means, and is emulated so that it can be handled as a magnetic disk from the outside. In FIG. 2, 10 is a common bus, 11 is connected to multiple host computers,
The semiconductor disk device of this embodiment has a plurality of directors, each of which controls a channel that is an interface with the outside and emulates a magnetic disk. Further, in the figure, 12 is a track memory for storing data, 13 is a bus arbiter that arbitrates the right to use the common bus 10, and 14 is necessary for exclusive control of one or more devices emulated by the semiconductor disk device. This is an exclusive control information storage device that stores information, and includes a data storage device N15 according to the present invention. This exclusive control information storage device 14 is accessed by a plurality of directors 11 and is controlled by an exclusive control storage access right arbitration device 16. The director 11 also includes a microprocessor (MPU) 16, a ROM 17, and a RAM.
In addition to 18, it has a channel control circuit 19 and a common bus control circuit 20. In addition to the data storage device 15 mentioned above, the exclusive control information storage device 14 also includes the data transfer circuit 2.
1 and a common bus adapter 22 are provided.

This data recording device has a configuration as shown in FIG. In the same figure, 30 is a memory as a storage means for actually storing data, and as shown in FIG. and memory 1 are provided.

31 is a memory selection table which specifies the above-mentioned memory O and memory 1 as n-bit memories as shown in FIG. 4;
32 is an exclusive OR gate that generates a memory switching signal by generating the output signal of the memory selection table as it is when reading a record, and by inverting the signal when updating a record; A record number address converter 35 outputs a record head address, and a counter 35 counts the number of data in a record. This counter 35 performs a counting operation at the falling edge of the input signal.

40 is an adder for adding the output of the record number address converter 33 and the output of the counter 35 to obtain an address in the memory for reading and writing data; 36, 37.3
Reference numeral 8 indicates a latch that outputs the input signal as it is when the latch input is active, and holds the input signal when the latch input was last active when the latch input is inactive. In this embodiment, these members as a whole constitute a storage means and a conversion table control section.

Next, the operation of this data storage device will be explained.

(1) Reading a record As shown in FIG. 5, a pulse is issued to the access start signal after the record selection signal indicating the record number and the R/W (read/update signal) are determined to be inactive (read). These signals are held in the latches and the counter 35 is set to 0 and initialized. The record number is output to the output of the latch 37, and the update signal is inactive, so the memory selection table 31 indicates that the record that is currently being read is
It sends a signal indicating which memory 〇 or memory 1 is valid. The output of latch 37 is held inactive, the read/write signal of memory 30 becomes read, and one input of exclusive OR gate 32 becomes inactive. The output of the memory selection table 31 is input to the other input of the exclusive OR gate 32, and since one input is inactive, the output of the exclusive OR gate 32 is the output of the memory selection table 31. and is input to the memory switching signal, so that the memory 30 that is shown to be valid by the memory selection table 31 is selected.

The record number address converter 33 inputs the record number, outputs the start address of the record, and converts it to the adder 40.
is input to one input terminal of. At this time, adder 40
Since the output of the counter 35, which is the other input, is O, the output of the adder 40 indicates the start address of the record. When the strobe signal becomes active, memory 30 is accessed and the first word of the record is output. When the strobe signal becomes inactive, the counter 35 performs a counting operation and its output becomes 1, and the output of the adder 40 indicates the second address from the beginning of the record. Next time the strobe signal becomes active,
The second word of the record is output. Similarly, the contents of the records are sequentially output.

(2) Record update As shown in FIG. 6, after the record selection signal indicating the record number and the R/W (read/update signal) are confirmed to be active (update), a pulse is issued to the access start signal, These signals are held in latch 37 and latch 36, respectively, and counter 35 is initialized.

Since the record number is output to the output of the latch 37 and the update signal is inactive, the memory selection table 3
1 means that the record you are currently trying to read is in memory O
It outputs a signal indicating which of memory 1 and memory 1 is valid. The output of latch 36 is held active;
The read/write signal of the memory 30 becomes a write, and one input of the exclusive OR gate 32 becomes active.

The output of the memory selection table 31 is input to another input of the exclusive OR gate 32, and since one input is active, the output of the exclusive OR gate 32 is input to the memory selection table 31. Since the output is an inverted version of the output of , and is input to the memory switching signal, the memory other than the one indicated as valid by the memory selection diple 31 is selected.

The record number/address converter inputs the record number and outputs the start address of the record, which is input to one input terminal of the adder 40. At this time, the output of the counter 35, which is the other input of the adder 40, is O, so
The output of adder 40 indicates the start address of the record. After the data is determined, the strobe is activated and the data is written to the start address of the record that is not valid in the memory 30. When the strobe is set inactive, the counter 35 performs a counting operation, and the output value becomes 1, and the output of the adder 40 indicates the second address from the beginning of the record. When the strobe is activated again after the next data is determined, that data is written to the second address of the non-valid record. In this way, data is written sequentially. When the last data has been successfully written, the strobe is made inactive and then the update signal is made active. Then, the latch holds the inverted value of the signal indicating which memory 0 or memory 1 is valid for the record that is currently being updated, and the value for the record that is currently being updated in the memory selection table 31 is inverted. written.

In other words, it is assumed that the memory to which data has just been written is valid. Records are updated in the manner described above.

In addition, if the record update was not performed normally,
Since no update signal is issued, the contents of the record that was attempted to be updated before starting the update are retained without being destroyed.

In this embodiment, if the size of the record in the memory is set to two values, the record number address converter and adder 40 in FIG. 3 are substantially unnecessary, and the hardware can be reduced. . That is, as the output of the adder 40, some low-order bits may be used as the output of the counter 35, and the high-order bits may be used as the output of the switch.

Therefore, according to this embodiment, the storage means is provided with two memories, memory 〇 and memory 1, and when updating data, new data is stored in the memory on the side that is not currently used, that is, the side that is not valid, of the record storage area. Since the display of the memory selection table is changed after the new data is successfully stored in the record, even if the data to be updated is interrupted midway, the previous data is not damaged at all and the display in the memory selection table is changed. Since it is stored in memory, it does not affect the entire system. Furthermore, according to this embodiment, the memory selection table 31 does not need to be particularly initialized, so the circuit configuration can be made simple.

(Effects of the Invention) As explained above, according to the present invention, a data storage device is provided with a double record storage area in the storage means, and when data is updated, new data is stored in one storage area that is currently being used. In addition to providing a storage means for storing data in the record storage area on the side that is not currently occupied, a memory selection table is also provided to display which record storage area is currently valid, and the above new data is successfully stored in the record. After confirming the above, we provided a table control unit that changes the display of the memory selection table, so when updating data, new data is stored in the record storage area that is currently not in use, and the table The control unit changes the display of the memory selection table after confirming that the above new data has been successfully stored in the record.
Even if the data to be updated is interrupted midway, the data of the record immediately before that record is stored in the other record storage area and will not be destroyed. Therefore, even if data writing stops mid-way during data update, the record before the update will not be deleted and will still exist, and even if a failure occurs during data update and data update is interrupted, the system will go down. This has the effect that problems such as the above do not occur and reliability can be improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of the present invention, FIG. 2 is a block diagram showing a device using the data storage device according to the invention, and FIG. 3 is a block diagram showing an embodiment of the data storage device according to the invention.
FIG. 4 is a diagram showing the memory selection table and memory contents of the data storage device shown in FIG. 3, and FIGS. 5 and 6 are time charts showing the operation of the data storage device shown in FIG. 3. . 1...Storage means 4...Repeat table control unit memory A selection table Memory 〇 Memory - 1 Memo 1 Note 1 Note 1 No. i Down table ε Memory Uchikun V Pond example's actual action No. 5 Figure disaster example 1Q action No. 6vA m, number of data

Claims (1)

[Scope of Claims] A data storage device having a storage means for storing data composed of a plurality of words as a record, and in which the data composed of a plurality of words is a unit of data update, wherein records are stored twice in the storage means. In addition to providing a storage area, when updating data, a storage means is provided to store new data in the record storage area that is currently not in use among the record storage areas, and it also displays which side of the record storage area is currently valid. A data storage device comprising: a memory selection table for storing the new data; and a table control unit for changing the display of the memory selection table after confirming that the new data has been properly stored in the record.