JPH10187541A - Data storage system and cache control method to be applied to the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain the improvement of efficiency in the use of system resources as a result by preserving a swap file as needed without generating any useless storage area in a semiconductor disk device especially when executing swap processing at the swapping function of system concerning a non-volatile cache system utilizing the semiconductor disk device. SOLUTION: When this system has a semiconductor disk device 1 as the external storage device of host system 4 having the swapping function and the swap file due to the swapping function is set, at the time point when the data write request of swap file is really generated from the host system 4 in the state of securing the logical file area of swap file, a controller 3 executes operation for writing data into the file area secured on the semiconductor disk device 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a computer system, and includes a magnetic disk drive and a flash EEP.
More particularly, the present invention relates to a data storage system having a so-called disk cache function.

[0002]

2. Description of the Related Art Conventionally, a computer system employs a so-called disk cache function (disk cache system) as a technique for eventually increasing the access speed of a magnetic disk device which is indispensable as an external storage device. ing. The magnetic disk device is usually composed of a hard disk drive (HDD) and is a large-capacity file device. However, the access speed is lower than that of a main memory composed of a semiconductor memory.

For this reason, the above-mentioned disk cache system compensates for the low-speed access operation of the HDD,
In particular, the access speed is increased for frequently used information. DRA is included in the disk cache system.
There is a method (also called smartdrive) in which a partial storage area of a main memory (volatile IC memory) composed of M is used as a cache area of an HDD. However, in this method, the main memory is cleared when the power is turned off.
The cache system does not function, but becomes effective after the power is turned on, and exhibits a so-called learning effect. The learning effect is H
When a cache area is accessed in response to a DD access, the cache area is not hit at first, but subsequently accessed data is stored in the cache area to exert a cache function.

Therefore, in the above-described method, even in the case of an operating system (OS) or an application program (AP) which is frequently used, the cache system functions effectively at the time of the first access to the HDD at power-on. do not do. For this reason, with the enlargement of the OS and the AP, the slow access speed of the HDD has an influence, and the prolonged time required for startup has become a problem.

Accordingly, a disk cache system using a semiconductor disk device composed of a flash EEPROM (flash memory) has been proposed.
The semiconductor disk device is a nonvolatile storage device, and
The access speed is faster than DD. Therefore, unlike the cache system using the main memory, the data in the cache area is retained even when the power is turned off, and the cache function can be effectively exhibited when the power is turned on. In addition, HDD
Therefore, a high-speed buffer function, which is a cache function, can be realized.

[0006]

According to the nonvolatile cache system using the semiconductor disk device,
In particular, the cache function for the HDD when the power is turned on can be effectively exhibited. It is desirable to operate such a cache system efficiently to improve the performance of the computer system. That is, by setting what kind of data is to be stored in the cache area using the storage area of the semiconductor disk device, and setting the cooperative function with the HDD, the cache system can be operated efficiently. .

By the way, in computer systems, a method called a swapping function is well known as a technique for improving the use efficiency of the main memory of the system. This function is a storage device that saves a file such as a program stored in the main memory (referred to as a swap file) to an HDD or the like as a secondary storage device and returns the HDD to the main memory when used. Perform swap operations to exchange files between. This is a method for improving the use efficiency of system resources.

In this swap processing, there is a method in which the above-mentioned semiconductor disk device is used as a cache area of the HDD. Specifically, when a swap file is set from the system (OS), a file area for storing the swap file is secured in the semiconductor disk device. However, the system only requests the reservation of a logical file area at the time of setting the swap file, and usually issues a write request for actually saving the data of the swap file in the secondary storage device at another occasion. For this reason, the file area secured in the semiconductor disk device by setting the swap file is an unused area where data is not actually written. Therefore, as a result, a useless storage area is generated in the semiconductor disk device, which causes a reduction in the use efficiency of system resources.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a nonvolatile cache system using a semiconductor disk device, particularly when a swapping process is performed in a swapping function of the system, so that a useless storage area is generated in the semiconductor disk device. Instead, a swap file is saved as needed, and as a result, the use efficiency of system resources is improved.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a data storage system comprising a semiconductor disk device comprising a flash EEPROM as an external storage device of a computer system having a swapping function, and setting a swap file by the swapping function of the computer system. Means to secure a logical file area of the swap file when the data is written, and when the data write request of the swap file is actually issued from the computer system, the data write operation to the file area secured in the semiconductor disk device is performed. The data comprising the means to be executed is a storage system.

With such a system, a logical file area is secured when a swap file is set by the swapping function of the system, but a physical file area of the semiconductor disk device is secured in response to an actual data write request. Is done. Therefore, just setting the swap file does not set the physical file area of the swap file in the semiconductor disk device, so that there is no useless storage area where data is not stored in the semiconductor disk device until an actual data write operation occurs. Such a situation can be prevented. Therefore, the storage area of the semiconductor disk device can always be used effectively.

According to a first aspect of the present invention, there is provided a data storage system including a magnetic disk device and the semiconductor disk device as the external storage device, wherein the cache system causes the semiconductor disk device to function as a cache memory of the magnetic disk device. Apply. The cache system controls access as a logical drive in which a magnetic disk device and a semiconductor disk device are integrally configured, and when a swap file is set by the swapping function of the computer system, the swap file is used as a logical file area of the logical drive. Of the swap file, and when the computer system actually issues a request to write the data of the swap file, secures a physical file area for saving the swap file on the semiconductor disk device or magnetic disk device and saves the swap file. Have means to do so.

As a second aspect of the present invention, the cache control means writes overflow data to a magnetic disk device when writing data of a swap file to a semiconductor disk device in response to a data write request from a system. Put in.

As a third aspect of the present invention, when the swap file is set by the swapping function, the cache control means secures a logical file area of the swap file as a virtual file area in the magnetic disk device. At the time when the computer system actually issues a swap file data write request,
The data of the swap file is written to an area secured in the semiconductor disk device. According to such a method, for example, when a system check process is performed by the OS of the system, access to the virtual file area of the magnetic disk device is performed, and functions such as response emulation can be easily realized.

As a fourth aspect of the present invention, the cache control means erases the swap file stored in the semiconductor disk device when the computer system is started, and always stores only the newly written swap file in the semiconductor disk device. Save. At this time, the cache control means clears the address information registered in the address conversion table means and logically deletes the swap file stored in the semiconductor disk device. According to such a method, unnecessary swap files before the start of the system are deleted from the semiconductor disk device, so that the ill effect of saving useless files can be eliminated and the use efficiency of the semiconductor disk device can be improved.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a main part of a disk cache system related to the embodiment of the present invention, and FIG. 2 is a block diagram showing a main part of a computer system related to the embodiment. (Disk Cache System) As shown in FIG. 1, a disk cache system according to the present embodiment is a computer system such as a personal computer, which is a semiconductor device configured from a flash EEPROM as a cache memory of an HDD 2 as an external storage device. The cache function is exhibited using the disk device 1. A cache system controller (hereinafter simply referred to as a controller) 3, which is a main component of the system, is realized as a type of device driver (software) that functions under the control of the OS of the computer system. The controller 3 includes the semiconductor disk device 1 and the HDD 2
, The data input / output control (cache operation control) is executed via the respective device drivers (flash memory driver and hard disk driver). Further, the controller 1 is configured so as to be interposed between the host system 4 including the OS and the application program (AP) and each of the disk devices 1 and 2.
In response to the write command, the semiconductor disk device 1 and the HDD 2 are controlled as a so-called integrated storage system.

Here, the host system 4 of the present embodiment
Has a so-called swapping function, and executes a swap process for exchanging a swap file between the main memory 23 and the secondary storage device (the HDD 2 in the present embodiment). When a swap file is set, the host system 4 normally registers the file on a file management table such as a FAT (file allocation table) by the OS to logically secure a file area for the swap file. Here, the file area secured in this way is called a logical file area.

As will be described later, even if a swap file is set by the swapping function, the controller 3
Instead of securing the file area of the semiconductor disk device 1 immediately, the file system of the semiconductor disk device 1 is secured and the data is written when the host system 4 actually requests the writing of the data of the swap file. (Computer System) The disk cache system of the present invention is applied to a computer system as shown in FIG. As the computer system of the present invention, a PC is used as a local bus to which peripheral devices are connected.
It is assumed that the CPU 22 and the PCI bus 20 are connected via the host / PCI bridge 21 using the I bus 20.

The computer system includes a main memory 23 connected to a bridge 21 and a PC card controller 24 compatible with a card bus connected to a PCI bus 20.
, HDD2, flash drive (ATA specification drive) 26, and floppy disk drive (FDD)
27, and a BIOS ROM 28 storing a basic input / output system (BIOS). It is assumed that the semiconductor disk device 1 shown in FIG. 1 includes a flash memory card 25 controlled by a PC card controller 24 and a flash drive 26. FDD
Reference numeral 27 denotes O by a floppy disk as an exchange medium.
Various drivers such as S, AP, or a cache system driver related to the present invention are installed in the system. The HDD 2 and the flash drive 26 or the flash memory card 25 are assigned different drive numbers (# 0, # 1). The OS and the AP of the host system 4 treat the HDD 2 and the semiconductor disk device 1 as drives different from each other as a hardware configuration. Therefore, in each storage area of the flash drive 26 or the flash memory card 25 which is the semiconductor disk device 1, the OS and the AP are transmitted via the cache system controller 3 for the storage areas other than the storage area used as the cache area related to the present invention. Can be used as a normal external storage device. (Swap processing of this embodiment) In the system configuration as described above, the operation of this embodiment will be described with reference to the conceptual diagram of FIG. 3 and the flowchart of FIG.

In this embodiment, as shown in FIG. 3, an external storage device (secondary storage device for the main memory 23) including the controller 3 from the host system 4 has the semiconductor disk device 1 and the HDD 2 integrated. Is handled as the logical drive 10 that has been used. In addition, controller 3
In response to an access request from the host system 4, an address to be accessed from the host system 4 (hereinafter referred to as a logical address) and the semiconductor disk device 1 or the HD
It has an address conversion table 30 for managing a correspondence relationship with an address (hereinafter, referred to as a physical address) for designating a storage area of D2. The controller 3 can logically secure a designated file area in, for example, a storage area of the semiconductor disk device 1 according to the access from the host system 4 by the address conversion table 30. As will be described later, the controller 3 clears the logical address in the address conversion table 30 to eliminate the correspondence between the logical address and the physical address. Can be deleted.

When the swap file is set by the swapping function, the host system 4 secures a logical file area of a file size for storing the swap file (steps S1 and S2). That is, the host system 4 performs a swap process for storing a swap file such as an unused program stored in the main memory 23 in the logical drive 10. In this swap processing, the OS registers the file on a file management table such as a FAT (file allocation table) to secure a logical file area for the swap file (the swap file area 10A in FIG. 3).

Here, when the swap file is set by the host system 4, the controller 3 registers the logical address on the address conversion table 30 and
A process of allocating the virtual file 2A to the DD 2 may be executed. By securing such virtual files,
For example, when a system check process is performed by the OS of the host system 4, the virtual file 2A to which the data of the HDD is not written can be accessed, so that response emulation and the like can be easily executed.

The controller 3 does not secure a file area (a storage area based on a physical address) in the semiconductor disk device 1 until a request for writing data of a swap file is issued from the host system 4 (N in step S3).
O). Normally, even if a swap file is set and a logical file area is secured, the host system 4 executes the swap file data write request at another opportunity.

On the other hand, when a write request for data of the swap file is issued from the host system 4, the controller 3 registers a logical address on the address conversion table 30 and writes the data of the swap file on the semiconductor disk device 1. (The actual file area 1A shown in FIG. 3). Then, the data of the swap file is written to the secured file area (step S3).
YES, S4). At this time, when the data of the swap file overflowing from the file area secured on the semiconductor disk device 1 occurs, the controller 3
The overflow data is written to the file area secured on the HDD 2 (steps S5 and S6).

By such processing, the data of the swap file is written on the semiconductor disk device 1 and the swap file transferred from the main memory 23 is stored. The host system 4 requests the logical drive 10 to access the swap file as necessary, and sets the swap file transferred from the logical drive 10 in the main memory. As a result, the swap file is exchanged between the main memory 23 and the logical drive 10 as the secondary storage device. here,
In the present embodiment, the controller 3 responds to an access request from the host system 4 to the logical drive 10,
The swap file stored in the semiconductor disk device 1 is read and transferred. Therefore, the access can be performed at a higher speed as compared with the case where the access is made from the HDD 2, and as a result, a high-speed swap process can be realized.

Next, it is assumed that the operation of the OS of the host system 4 has been completed and the system power has been turned off (YES in step S7). Thereafter, when the system power is turned on and the OS is restarted, in the present embodiment, the controller 3 deletes the swap file (YES in step S8, S9). Specifically, the controller 3
Clears the logical address corresponding to the swap file registered on the address conversion table 30 when the system is started, and logically deletes the swap file stored on the semiconductor disk device 1. That is, by clearing the logical address, the address conversion table 30 is cleared.
In the above, since the correspondence relationship with the physical address of the semiconductor disk device 1 disappears, the swap file stored on the semiconductor disk device 1 has been substantially deleted.

By such processing, the swap file is not normally required when the OS is terminated (or the system power is turned off). However, since the semiconductor disk device 1 (or the HDD 2) is non-volatile, even if the power is turned off, the data remains stored without being erased. Therefore, the unnecessary swap file remains stored, and the storage area of the semiconductor disk device 1 is wasted. Thus, as in the present embodiment, when the system is started (when the OS is started), the controller 3 executes the process of clearing the address conversion table 30 so that the unnecessary swap file stored in the semiconductor disk device 1 is deleted. Logically erase. Further, even in the case of emergency termination of the OS or emergency power off, the controller 3 executes the clearing process of the address conversion table 30 to logically delete unnecessary swap files.

As described above, according to the present embodiment, when a swap file is set by the swapping function of the host system 4, a logical file area is secured, but an actual data write request is made on the semiconductor disk device 1. Until the error occurs, no file area is reserved. Therefore, the semiconductor disk device 1 does not have an unused area in which the data of the swap file is not actually written, and the semiconductor disk device 1 has the file area of the swap file when the data write request actually occurs. Will occur.

When the system is started (when the OS is started)
In addition, since the swap file stored in the semiconductor disk device 1 is logically erased, the unnecessary swap file previously stored does not maintain the state stored in the semiconductor disk device 1 and is always kept. Only the newly written swap file can be saved.

[0030]

As described above in detail, according to the present invention, in a nonvolatile cache system using a semiconductor disk device, when a swap process in a swapping function of a computer system is executed, a swap file is actually stored. The data is written to the semiconductor disk device at the time of the write request, and the swap file is stored. Therefore, it is possible to prevent the unnecessary storage area of the semiconductor disk device from being generated and prevent the unnecessary storage area of the semiconductor disk device from being used, and to always effectively use the storage area. In addition, since unnecessary swap files can always be stored by erasing unnecessary swap files when the system is started, useless storage areas can be prevented from being generated. As a result, the use efficiency of the resources of the computer system can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main part of a disk cache system according to an embodiment of the present invention.

FIG. 2 is an exemplary block diagram showing a main part of a computer system related to the embodiment;

FIG. 3 is an exemplary block diagram showing the concept of a logical drive related to the embodiment.

FIG. 4 is a flowchart for explaining an operation related to the embodiment;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor disk device 2 ... Hard disk drive (magnetic disk device) 3 ... Cache system controller (cache control means) 4 ... Host system (OS, AP) 10 ... Logical drive 20 ... PCI bus 21 ... Host / PCI bridge 22 ... CPU 23 main memory 24 PC card controller 25 flash memory card 26 flash drive 27 floppy disk drive (FDD) 28 ROM (BIOS) 30 address conversion table

Claims (8)

[Claims] 1. A data storage system applied to a computer system having a swapping function and using an external storage device of a semiconductor disk device constituted by a flash EEPROM, wherein a setting of a swap file by the swapping function of the computer system is provided. Means for securing a logical file area of the swap file, and securing an area for storing the swap file in the semiconductor disk device in response to a write request for data of the swap file from the computer system. And a means for writing the data. 2. The method according to claim 1, wherein the magnetic disk drive and the flash E are applied to a computer system having a swapping function.
A data storage system using each external storage device of a semiconductor disk device composed of an EPROM, wherein the data input / output of the magnetic disk device and the semiconductor disk device is controlled, and the semiconductor disk device is connected to the magnetic disk. A cache control unit that functions as a cache memory of the device, wherein the cache control unit secures a logical file area of the swap file when a swap file is set by the swapping function of the computer system. Means for securing the area for storing the swap file in the semiconductor disk device and writing the data in response to a write request for the data of the swap file from the computer system. Memory Stem. 3. A data storage system applied to a computer system having a swapping function and using each external storage device of a semiconductor disk device composed of a magnetic disk device and a flash EEPROM, wherein the magnetic disk device and the semiconductor A cache control unit configured to perform access control as a logical drive in which the disk device is integrally configured, wherein the cache control unit logically controls the logical drive when a swap file is set by the swapping function of the computer system. A file area of the swap file is secured as a file area, and when a request for writing data of the swap file is actually generated from the computer system, the semiconductor disk device or the magnetic disk device Data storage system, characterized in that to ensure the physical file area for storing serial swap file comprising means for storing the swap file. 4. The cache control means includes means for writing overflow data exceeding an area secured in the semiconductor disk device to the magnetic disk device when writing the data of the swap file to the semiconductor disk device. 2. The data storage system according to claim 1, comprising: 5. The cache control means, when a swap file is set by the swapping function, reserves a logical file area of the swap file as a virtual file area in the magnetic disk device,
2. The device according to claim 1, further comprising: a unit for writing the data of the swap file to an area secured in the semiconductor disk device when a request for writing the data of the swap file is actually generated from the computer system. Item 3. The data storage system according to Item 2. 6. The cache control means erases the swap file stored in the semiconductor disk device when the computer system starts up, and always stores only the newly written swap file in the semiconductor disk device. 3. The data storage system according to claim 1, further comprising: 7. The cache control unit includes an address conversion table unit for managing a correspondence relationship between an address of an access request from the computer system and an address of the semiconductor disk device, and when starting up the computer system. 6. A data storage system according to claim 5, further comprising means for clearing address information registered in said address conversion table means and logically erasing said swap file stored in said semiconductor disk device. 8. A magnetic disk drive and a flash EE in a computer system having a swapping function.
A cache control method applied to a data storage system using each external storage device of a semiconductor disk device composed of a PROM, wherein the semiconductor disk device functions as a cache memory of the magnetic disk device. A process for securing a logical file area for the swap file when a swap file is set by the swapping function; and a process for writing the swap file data from the computer system to the semiconductor disk device according to the write operation of the swap file. A process for securing an area for storing the data, a process for writing the data of the swap file to the semiconductor disk device, and a process for storing the swap file stored in the semiconductor disk device when the computer system is started after being stopped. And deleting the backup file.