JP2002108569A - Volatile external storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve not only high diverting performance and the simplicity of the extension of a storage capacity but also processing performance when applying swap processing instead of extending a main memory. SOLUTION: A format part 14 of an external storage device 10 is started by a reset signal transmitted from a computer 20 when power is supplied to the host computer 20. Then, the format part 14 refers to a table 142 in a non- volatile storage part 140 according to the state of a switch 13, and selects a format program 141 specific to an OS operating on the computer 20 which is made correspond to the state from the non-volatile storage part 140, and executes the format of the a volatile storage part 12 according to the program 141. When a read/write instruction for file access is transmitted from the host computer 20, an interface 11 receives the instruction, and performs access to the volatile storage part 12 according to the instruction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a volatile external storage device suitable for connection to a computer.

[0002]

2. Description of the Related Art When a computer performs a certain process, there is a case where there is not enough free space in the main memory to perform the process. The main memory is expensive in storage unit price among storage devices, and the shape, access speed, error correction method, etc. differ depending on the corresponding computer, so the type of main memory used in a certain computer differs. It is difficult to use on other computers. For this reason, it is costly to expand the main memory. Further, since the number of slots for adding a main memory is limited, there is a limit in adding a large-capacity main memory.

Therefore, conventionally, the above-described specific processing can be performed without adding a main memory by performing the following swap processing. When performing a swap process, a non-volatile storage device such as a magnetic disk device having a larger capacity than the main memory and a slower read / write speed is designated as a swap destination, and a storage space including the main memory and the swap destination is allocated. Use as a virtual storage space. If the data required for processing is not in the main memory but is in the swap destination, the necessary data is copied from the swap destination to the main memory and used. At this time, if there is no free space in the main memory, unused data in the main memory is copied to a swap destination to make free space.

The nonvolatile storage device at the swap destination is not controlled by hardware like a main memory, but is controlled by software. For this reason, there is no problem such as compatibility with hardware such as the main memory and a difference in access speed, and the feature is that the applicability is high.

[0005]

However, in the above-mentioned conventional swap processing, it is necessary to perform a copy processing between a nonvolatile storage device having a low read / write speed and the main memory. There is a problem that the processing performance is worse than when performing

The present invention has been made in consideration of the above circumstances, and has as its object to provide not only a high diversion capability that can be easily used for various types of computers and an ease of adding a storage capacity, but also that the To provide an external storage device capable of improving the processing performance when applying a swap process instead of adding a main memory in order to cope with a case where there is not enough free space in a main memory when performing a process. It is in.

[0007]

According to a first aspect of the present invention, there is provided an external storage device which can be used by being connected to a computer, comprising: a volatile storage unit; An interface for receiving a read / write command for file access and accessing the volatile storage unit according to the command, and a file system of an operating system (OS) operating on a computer that can use the external storage device are managed. A switch for selectively designating the format of a file to be stored, and a file format prepared for each of different types of OSs operating on various computers that can use the external storage device and managed by a file system of the OS. Format program for format processing conforming to A non-volatile storage unit for storing a table (switch state-format program correspondence table) indicating a relation between each state of the switch and the format program specific to the format specified by the state in a tabular form; Is activated by receiving a reset signal from a computer connected to the external storage device, and refers to the table according to the state of the switch to select a format program corresponding to the state from the nonvolatile storage unit. ,
Formatting means for executing formatting processing for formatting the volatile storage unit according to the selected format program.

In the external storage device having such a configuration, a read / write command for file access, that is, a read / write command of the same format as given to a magnetic disk device or the like is received by the interface. The interface allows the volatile storage unit to be accessed in the same way as for the magnetic disk drive.

For this reason, when data is read from or written to the external storage device (volatile storage unit) from a computer connected to the external storage device and used, the external storage device is magnetically connected. It can be handled in the same way as a disk device. In addition, even in the case of different types of computers, the read / write instructions to the magnetic disk device are controlled by software, so that the external storage device having the above configuration is more versatile than a storage device such as a memory controlled by hardware. . Also,
Since it is an external storage device, it is possible to increase the storage capacity regardless of the memory expansion slot of the computer. When the external storage device is connected to a different type of computer and used, the setting of the state of the switch is performed by changing the setting of the switch to an OS (a file format managed by a file system) that runs on the new computer.
May be changed to a switch state corresponding to

When a computer connected to the external storage device performs a specific process and there is not enough free space in the main memory to perform the process, the external storage device is used as a swap destination. If used, a volatile storage unit (volatile storage device) that can be accessed faster than a volatile storage device such as a magnetic disk device is used for the external storage device. The processing performance can be improved as compared with the case where the device is used as a swap destination.

Here, when the power of the computer connected to the external storage device is turned on, the formatting process for formatting the volatile storage unit is executed by the reset signal sent from the computer. When the power of the computer is turned on, the volatile storage unit (an external storage device including the same) can always be used as a disk device from the computer.

Since the external storage device of the present invention uses the volatile storage unit as described above, when the power of a computer connected to the external storage device is turned off, a battery backup or the like is performed. Unless there is a special means, all data in the storage unit will be lost. However, even in such a case, the external storage device of the present invention correctly operates as a swap destination. The reason will be described below.

When the swap process is performed, data written to the storage unit of the external storage device that is the swap destination is data written to the main memory of the computer. Main memory data is stored when the computer is turned off.
Therefore, when the power of the computer is turned off, there is no problem even if data in the storage unit of the external storage device is lost.

An external storage device according to a second aspect of the present invention has the following function, that is, an external storage device according to the second aspect, connected to the interface of the external storage device according to the first aspect. Sent from the driver software that is always executed when the computer is turned on.
In addition to adding a function of receiving format information designating the format of a file managed by the file system of the OS operating on the computer, the external device according to the second aspect is replaced with the switch state-format program correspondence table. A table (format information-format program correspondence) showing a relationship between various format information that may be transmitted from driver software of various computers that can use the storage device and a format program specific to the format specified by the information. Table), the format means uses the format information sent from the driver software of the computer when the power of the computer used by connecting the external storage device is turned on. Table (format information-format program correspondence table) to select a format program corresponding to the information, and execute a format process for formatting the volatile storage unit according to the selected format program. It is characterized by.

The external storage device having such a configuration receives format information from driver software which is always started when the power of the computer is turned on.
Select the corresponding format program each time,
A format process for formatting the volatile storage unit is performed according to the selected format program. Therefore, even when the external storage device is connected to a different type of computer and used, unlike the external storage device according to the first aspect, it is not necessary to change the setting of the switch. All you have to do is switch to a new computer. This external storage device can be used as a formatted disk device whenever the power of a computer connected to the storage device is turned on. Therefore, even when a volatile memory is used as the storage unit, it can be used as a swap destination without any problem.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. First Embodiment <Configuration of First Embodiment> FIG. 1 is a block diagram of a computer system mainly showing the configuration of an external storage device according to a first embodiment of the present invention.

In FIG. 1, for example, when the host computer 20 performs a specific process, the external storage device 10 has a sufficient free space in a main memory (not shown) in the computer 20 to perform the process. Used as a swap destination when there is no area.

The external storage device 10 includes an interface 11
, A volatile storage unit 12, a switch 13, and a format unit 14.

The interface 11 exchanges commands (read / write commands, etc.) and data with the host computer 20. The interface 11 receives a read / write command of the same format as a read / write command for accessing a file on the magnetic disk device from the host computer 20, and reads / writes data stored in the volatile storage unit 12. And returns the result to the host computer 20.

The volatile storage unit 12 stores data (here, file data) transferred from the host computer 20.
Is used to store The volatile storage unit 12 is composed of a volatile memory such as a RAM (Random Access Memory) that can be accessed at a higher speed than a nonvolatile storage device such as a magnetic disk device. Read / write for the volatile storage unit 12 is performed by the interface 11.

The switch 13 is, for example, a dip switch for holding a state necessary for the format unit 14 to select the format program 141. The state of the switch 13 depends on the format of a file managed by a file system of an operating system (OS) running on the host computer 20.
An appropriate state is set in advance.

The format section 14 is provided with a ROM (Read Onl
y), which has a nonvolatile storage unit 140 whose stored contents do not change even when the power is turned off. The nonvolatile storage unit 140 includes a format program 141 prepared for each of a plurality of predetermined OSs,
A table (switch state-format program correspondence table) 142 indicating the relation between each state of the switch 13 (state data representing the state) and the format program 141 associated with the state in a table format is stored.

The format program 141 writes predetermined constant information in a designated area of the volatile storage unit 12 so as to conform to a file format managed by a corresponding OS file system. That is, it is software for formatting the volatile storage unit 12.

Generally, when the power of the host computer 20 is turned on, a reset signal for initialization is sent to all peripheral devices. In the present embodiment, the reset signal is connected to the host computer 20 so as to be received by the format unit 14 of the external storage device 10. When receiving the reset signal from the host computer 20, the format unit 14 selects the format program 141 associated with the state from the plurality of format programs 141 by referring to the table 142 according to the state of the switch 13. Then, the format of the volatile storage unit 12 is executed according to the selected format program 141.

<Operation of First Embodiment> Next, the operation of the configuration of FIG. 1 will be described with reference to the flowchart of FIG.
Now, as a result of turning on the power of the host computer 20,
It is assumed that the reset signal has been sent to all peripheral devices including the external storage device 10.

The reset signal sent from the host computer 20 to the external storage device 10 is received by the formatting section 14 (step S1). Then, the format unit 14 refers to the state of the switch 13 (Step S
2) After that, by referring to the table (switch state-format program correspondence table) 142 from the state (state data representing), the nonvolatile storage unit 1
40, a plurality of format programs 1 stored in
41, the program 141 associated with the state is selected (step S3). The selected format program 141 is stored in the external storage device 1
0 is prepared corresponding to the OS operating on the host computer 20 connected thereto.

The format section 14 is a volatile storage section 12
Conforms to the format of the file managed by the file system of the OS operating on the host computer 20, that is, the volatile storage unit 12 has the same format as that for the magnetic disk device from the file system of the OS. In order to be able to access (read / write) by a read / write command, the above step S
A format process for formatting the volatile storage unit 12 is executed according to the format program 141 selected in Step 3 (Step S4).

By this format processing, a read / write command (read command or write command) for file access in the same format as for the magnetic disk drive is sent from the host computer 20 to the interface 11 of the external storage device 10. In this case, the interface 11 receives a read / write command from the host computer 20 and reads data stored in the volatile storage unit 12 or writes data to the volatile storage unit 12 in accordance with the command. It can be performed. When executing a read / write command from the host computer 20, the interface 11 returns a result to the host computer 20.

<Effects of the First Embodiment> In the embodiment described above, the interface 11 in the external storage device 10 has a read / write command of the same format as a read / write command for file access to the magnetic disk device.
It is configured to receive a write instruction and perform a read / write operation on the volatile storage unit 12 in accordance with the instruction.

Therefore, access from the host computer 20 to the external storage device 10 can be handled in the same manner as access to the magnetic disk device. In addition, since the read / write command for file access to the magnetic disk device is controlled by software even in different types of computers, the external storage device 10 of the present embodiment capable of executing the read / write command.
Is more divertable than a storage device such as a memory controlled by hardware.

Further, since the external storage device 10 of the present embodiment is used by being externally connected to the host computer 20 via the interface 11, the storage capacity can be increased irrespective of the main memory expansion slot of the computer 20. It is.

Further, in the external storage device 10 of the present embodiment, the storage unit 12 accessed from the host computer 20 via the interface 11 can be accessed at a higher speed than a non-volatile storage device such as a magnetic disk device. A configuration using a volatile memory is applied. For this reason, when the host computer 20 performs, for example, a specific process, if the main memory does not have enough free space to perform the process, the external storage device 10 is used as a swap destination, so that the magnetic disk drive can be used. The processing performance can be improved as compared with a case in which is used as a swap destination.

The storage unit 12 of the external storage device 10
Is configured with a volatile memory as in the present embodiment, high-speed access to the storage unit 12 is possible, but when the power of the host computer 20 is turned off, unless a means such as a battery backup is applied, All the data in the storage unit 12 is lost. However, the external storage device 10 of the present embodiment operates correctly as a swap destination. The reason will be described below.

When the host computer 20 performs the swap processing, the data written to the storage unit 12, which is the swap destination, is the data written to the main memory of the computer 20. As is well known, the main memory has a property that data in the main memory is lost when the power of the computer is turned off. Therefore, there is no problem even if the data in the storage unit 12 disappears when the power of the computer 20 is turned off.

Further, the external storage device 10 of the present embodiment
Upon receiving a reset signal that is always transmitted when the power of the host computer 20 is turned on, the storage unit 12
Has the configuration to execute the format. With this configuration, when the power of the host computer 20 is turned on, the external storage device 10 (the volatile storage unit 12 therein) can be used as if it were a disk device in a formatted state. Therefore, the external storage device 1
Even when a volatile memory such as a RAM is used for the storage unit 12 in 0, it can be used as a swap destination without any problem.

Second Embodiment <Configuration of Second Embodiment> In the external storage device 10 according to the first embodiment described above, the host computer 20
When a reset signal output from the computer 20 is received when the power is turned on, the state of the switch 13 is referred to, and the format program 141 corresponding to the state is selected. In the external storage device 10 having such a configuration, when the external storage device 10 is connected to a different type of computer and used, the user operates the switch 13 to operate the file system of the OS running on the computer. It is necessary to change to the switch state corresponding to the format of the file managed by. However, such a switch operation is complicated, and an erroneous state setting may be performed.

In order to solve the above-mentioned problem of the configuration using the switch 13, an external storage device according to a second embodiment of the present invention to which a configuration in which a format program is automatically selected by driver software is applied.
This will be described with reference to the drawings.

<Configuration of Second Embodiment> FIG. 3 is a block diagram of a computer system mainly showing a configuration of an external storage device using a volatile storage device according to a second embodiment of the present invention. .

Referring to FIG. 3, the external storage device 30 comprises an interface 31, a volatile storage unit 32, and a format unit 34. Here, the external storage device 3
Note that 0 does not have a switch corresponding to switch 13 in FIG.

The interface 31 exchanges commands (read / write commands, etc.) and data with driver software (hereinafter referred to as driver software) 41 operating on the host computer 40. Here, the interface 31 is configured to also receive, from the driver software 41, format information indicating the format of a file managed by the file system of the OS running on the host computer 40.

The interface 31 includes the driver software 4
When the above-mentioned format information is received from No. 1, the format information is sent to the format section 34. Further, the interface 31 receives a read / write command of the same format as a read / write command for accessing a file on the magnetic disk device from the host computer 40 and reads / writes data from / to the volatile storage unit 32. The host computer 40
To return.

The volatile storage section 32 is composed of a volatile memory such as a RAM which can be accessed at high speed, similarly to the volatile storage section 12 in the external storage device 10 of FIG. It is used to store data (here, file data). Read / write for the volatile storage unit 32 is performed by the interface 31.

The format section 34 has a nonvolatile storage section 340 similar to the nonvolatile storage section 140 in FIG. The nonvolatile storage unit 340 stores a plurality of predetermined O
A table (format information-format program) that shows the correspondence between the format program 341 prepared corresponding to each S and the various format information and the format program 141 for executing the format process indicated by the format information. Correspondence table) 342 is stored.

The format section 34 is provided with the driver software 4
Format information sent from the interface 1
, The format information is referred to the table 342, the format program 341 associated with the format information is selected from the plurality of format programs 341, and the format program 341 is volatilized according to the selected format program 341. The format of the sex storage unit 32 is performed.

<Operation of Second Embodiment> Next, the operation of the configuration of FIG. 3 will be described with reference to the flowchart of FIG. First, driver software 41 corresponding to a file format managed by a file system of an OS operating on the computer 40 is installed in the host computer 40 to which the external storage device 30 is connected in advance.

In such a state, the host computer 4
0 is assumed to be turned on. As is well known, when a computer is turned on, driver software for peripheral devices connected to the computer is started. Also in the present embodiment, when the power of the host computer 40 is turned on, that is, when the host computer 40 starts up, the driver software 41 is started (step S11).

Then, the driver software 41 sends format information indicating the format of a file managed by the file system of the OS running on the host computer 40 to the interface 31 of the external storage device 30 (S12). The interface 31 sends the format information from the driver software 41 to the format unit 34 (Step S13).

The format section 34 has driver software 41
When the format information is received from the non-volatile storage unit 340 by referring to the table (format information-format program correspondence table) 342 based on the format information, From among them, the program 3 corresponding to the format information
41 is selected (step S14). The selected format program 341 is stored in the external storage device 30
Are prepared corresponding to the OS operating on the host computer 40 to which the is connected.

The format section 34 performs the processing in step S1
A format process for formatting the volatile storage unit 32 is executed according to the format program 341 selected in Step 4 (Step S15). Thus, the volatile storage unit 32 is formatted so as to conform to the file format managed by the file system of the OS running on the host computer 20.

After executing the format process in step S15, the format unit 34 returns a result (success / failure) of the format process to the interface 31 (step S16). In response, the interface 31
The result of the format processing in the format unit 34 is returned to the driver software 41 (step S17).

The driver software 41 is provided in the format unit 3
When the result (success / failure) of the format processing in step 4 is received from the interface 31, the result is determined (step S18). If the format processing is successful, the driver software 41 incorporates the external storage device 30 into the system as a disk device (step S1).
9). On the other hand, if it fails, the driver software 4
1 performs a process of failure to incorporate the device (step S2)
0).

As described above, it is assumed that the format processing in the format unit 34 has been successful and the external storage device 30 has been incorporated into the system as a disk device.
In this state, when a read / write command (read command or write command) for file access in the same format as that for the magnetic disk device is sent from the host computer 40 to the interface 31 of the external storage device 30 thereafter. In addition, the interface 31 receives a read / write command from the host computer 40, and reads data stored in the volatile storage unit 32 or writes data to the volatile storage unit 32 according to the command. it can. When the interface 31 executes a read / write command from the host computer 40, the interface 31
Returns the result to

<Effects of Second Embodiment> As described above, the external storage device 30 of the present embodiment is built in the host computer 40 to which the external storage device 30 is connected. From the driver software 41 corresponding to the file format managed by the file system of the OS running on the host computer 40, the corresponding format program 341 is determined based on the format information given when the host computer 40 is started up. , The volatile storage unit 32 is formatted in accordance with the format program 341.

Therefore, when the power of the host computer 40 is turned on, the external storage device 30 can always be used as a formatted disk device, and can be used as a swap destination. Therefore, the external storage device 30 of this embodiment has the effects of high diversion, easy increase of storage capacity, and improvement of data processing performance, similarly to the external storage device 10 of the first embodiment.

In this embodiment, the external storage device 30
May be selected (specified) by a switch as in the first embodiment (for the formatting process for formatting the volatile storage unit 32), which is compatible with the host computer 40 to which is connected. Instead, it is automatically selected (designated) by information of a format compatible with OS running on the computer 40 and transmitted from the driver software 41 incorporated in the host computer 40.

Therefore, even when the external storage device 30 of the present embodiment is connected to a different type of computer and used, the operation of changing the switch setting as in the first embodiment is not necessary. It can be used simply by connecting the external storage device 30 to a new computer.

[0057]

As described in detail above, according to the present invention, a volatile storage device (volatile storage unit) which can be accessed at a higher speed than a nonvolatile storage device such as a magnetic disk device can be used. The storage device is configured to execute a format process that conforms to a file format managed by the file system of the OS of the computer that uses the storage device. Since the configuration is provided with an interface for receiving and executing the same type of read / write instruction, high diversion and easy increase in storage capacity can be achieved.

According to the present invention, when the host computer performs, for example, a specific process, the external storage device of the present invention can be used as a swap destination even if there is not enough free space in the main memory to perform the process. By doing so, the processing performance can be improved as compared with the case where the magnetic disk device is used as a swap destination.

[Brief description of the drawings]

FIG. 1 is an exemplary block configuration diagram of a computer system mainly showing the configuration of an external storage device according to a first embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation in the first embodiment.

FIG. 3 is an exemplary block configuration diagram of a computer system mainly showing the configuration of an external storage device according to a second embodiment of the present invention.

FIG. 4 is a flowchart for explaining the operation in the second embodiment.

[Explanation of symbols]

10, 30 external storage device 11, 31 interface 12, 32 volatile storage unit 13 switch 14, 34 format unit 41 driver software (driver software) 140, 340 nonvolatile storage unit 141, 341 format Program 142: Table (switch state-format program correspondence table) 342: Table (format information-format program correspondence table)

Claims (2)

[Claims] An external storage device that can be used by being connected to a computer, comprising: a volatile storage unit; and a read / write command for file access from a computer connected to the external storage device. An interface for accessing the volatile storage unit in accordance with the following; a switch for selectively designating a file format managed by a file system of an operating system operating on a computer that can use the external storage device; A format program for a format process that is prepared for each of different types of operating systems that operate on various computers that can use the storage device and that is compatible with the format of a file managed by the file system of the operating system And no,
A non-volatile storage unit that stores a table indicating a relationship between each state of the switch and the format program specific to the format specified by the state in a tabular format; and a computer connected to the external storage device. Is activated by receiving a reset signal, and by referring to the table according to the state of the switch, a format program corresponding to the state is selected from the non-volatile storage unit, and the volatile storage is performed according to the selected format program. An external storage device comprising: a format unit that executes a format process for formatting a unit. 2. An external storage device that can be used by being connected to a computer, comprising: a volatile storage unit; and a read / write command for file access from a computer connected to the external storage device. According to the function of accessing the volatile storage unit, at the time of starting the driver software compatible with the external storage device incorporated in the computer,
An interface having a function of receiving format information that specifies a format of a file sent from the software and managed by a file system of an operating system operating on the computer; and on various computers where the external storage device can be used. A format program for a format process prepared for each operating system of a different type of operation and adapted to a file format managed by the file system of the operating system;
The table format shows a relationship between various types of format information that may be sent from the driver software incorporated in various types of computers that can use the external storage device and the format program specific to the format specified by the information. A nonvolatile storage unit in which a table is stored, and activated by receiving the format information transmitted from the driver software incorporated in the computer connected to the external storage device via the interface, By referring to the table with the information, a format program corresponding to the information is selected from the non-volatile storage unit, and a format program for executing a format process for formatting the volatile storage unit according to the selected format program is performed. And an external storage device.