JPS59220856A - Disc cache memory back-up system - Google Patents

Abstract

PURPOSE:To back up efficiently a disc cache memory at a power-off time by storing the disc address of data, which is not written yet on a disc, and corresponding unwritten data in a nonvolatile memory. CONSTITUTION:When all of a series of data which should be written on a disc device 30 are written in a disc cache memory 103, pointer information is loaded to a pointer register PREG107 in a control part 106. If power is turned off in this state, the control part 106 writes directory information, which is indicated by pointer information, in an area of a back-up memory 105 while an effective voltage is held. This operation is executed with respect to a series of linked directory information ending with the last directory information indicated by pointer information. At a power restoration time, the control part 106 accesses the back-up memory 105 to read out its contents from the start address and writes them in an area indicated by a disc address in the disc device 30.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a disk cache system that employs a one-store storage system, and in particular to a disk cache memory backup system that backs up the disk cache memory when the power is turned off. Regarding.

[Technical background of the invention]

In a disk cache system that completely adopts the store-through type, data to be written to the disk is first written to the disk cache memory in response to a write request to the disk. However, the CP from the disk controller
The completion of the write operation is notified to U (upper device), and then the write operation to the data 'ff disk of the disk cache memory is performed using the free time of the disk controller.

[Problems with background technology]

In the conventional disk cache system that adopts the store-through method, writing to the disk is performed effectively and the features of the system are utilized, but the zologram operation and the contents of the disk are processed in units of logical program completion. Since the system cannot be synchronized with the CPU, there is a drawback that an inconvenience may occur if the power of the system is cut off between the time when the CPU is notified of the completion of the write operation and the time when the actual write operation to the disk is completed. Of course, in order to eliminate this inconvenience, the disk cache memory may be backed up by a battery, but this method does not allow for a reduction in the size and weight of the device.

[Purpose of the invention]

This invention was made in response to the above circumstances, and its purpose is to provide a disk cache memory backup method that can efficiently back up the disk cache memory when the power is cut off in a disk cache system that adopts a store-through type. It's about doing.

[Outline of the invention]

In this invention, pointer information to the next directory information is added to the directory information stored in the directory memory, and by using this pointer information, a series of data stored in the disk cache memory is transferred to the disk. The configuration is such that the writing order can be managed, and a rewritable nonvolatile memory is provided at the bottom of the groove as a backup memory for the directory memory and disk cache memory, and at least the disk address and the directory information regarding unwritten data to the disk are provided when a power outage is detected. , and corresponding unwritten data are stored in nonvolatile memory. Further, in the present invention, unwritten data is written to the disk based on the contents of the nonvolatile memory after the power is restored.

[Embodiments of the invention]

FIG. 1 is a block diagram showing the configuration of a disk cache system according to an embodiment of the present invention. A disk controller designated by the reference numeral 10 in the figure controls the disk device 30'ff in response to a request from, for example, a CPU 20, which is a host device. The disk controller 10 is C
It has a CPU interface 101 that interfaces with the PU 20 and a device interface 102 that interfaces with the disk device 30.

The disk controller 10 also includes a disk device 30.
It also has a disk cache memory 103 that stores write/read data for the disk cache memory 103, and a directory memory 104'fr: in which directory information of the disk cache memory 103 is registered. Disk cache memory 103 Storage directory memory 104
is, for example, a RAM.

FIG. 2 shows the format of directory information. Directory information includes disk address DISK ADH1 write flag F, and pointer information Pi.

Disk cache memory address MEM ADR.

and size information 5IZE. The disk address DISK ADH indicates where write data is written to the disk device 30. The write flag F indicates the end of data import to the disk device 30 (“°0”)/
Unfinished ("1") ' Pointer information Pl indicates the storage location of the IJ information in the directory memory 104. The disk cache memory address MEM ADR is the disk cache memory 103 of the data to be written to the disk device 30. Indicates the storage location in.Size information 5IZEVi Indicates the size of the write data.

Referring again to FIG. 1, the disk controller 10 further includes a backup memory 105 composed of a rewritable non-volatile memory, and a control section 106 which is the core of the disk controller 10. Control unit 10
6 is composed of, for example, a microprocessor. The control unit 106 is provided with a pointer register (hereinafter referred to as PREG) 107 that holds pointer information Pi to directory information regarding the address of the disk cache memory 103 to be accessed next. CPU
interface 10 device interface 102;
Disk cache memory 103, directory memory 1
04, paraphrase memory 105, and rhyme 1 part 10
It is connected to a bus 108, such as a 6-channel microprocessor path.

Next, the operation of one embodiment of the present invention will be explained.

Now, in response to a disk write request from CPU 20,
A series of data to be written to the disk unit Hg3o is stored in the disk cache memory 1 in the disk controller 10.
It is assumed that all the information is written in 03. At this time, the write flag Fld logic 111'' in each directory information (in the directory memory 104) corresponds to a series of data written to the disk cache memory 103. In PREGL07 in 106, the first pointer in the directory information group where F is logic "1" in the write flag) l) Pointer information Pi (1 = k) The control unit 106 controls the CPU 20 when writing of the series of data to the disk cache memory 103 is completed.
Notify the user that @writing operation is completed. Thereafter, the control unit 106 includes the above series of data (disk device 30
) unwritten data to disk cache memory 1
03 to the disk device 30 is executed using free time.

The control unit 106 first accesses the directory memory 104f using the pointer information Pi(1=k) k loaded in the PREGJ 07 and reads the corresponding directory information. Next, the control unit 106 determines the disk cache memory end address MEM A in this directory information.
The corresponding data is read from the disk cache memory 103 based on the DR and the size information 5IZE. The control unit 106 sends the data to the device interface 10.
2 to the disk device 3θ, and makes it echo in the area indicated by the disk address DISKADH in the directory information. Note that the device interface 10
2 has input/output control 1 function, control + FtB J
o From 6 to the device interface 102, the directory information (disk address p3KADR,
the device interface 10 by giving the disk cache memory address (MEM ADR, and size information)
It is also possible to start 2f. When the data writing to the disk device 30 is completed, the control unit 106 sets the write flag F in the corresponding directory information in the directory memory 104 to logical nun, and sets the moromi inter information P I (1= to −
1-1) into PRF and G107. Next, the control unit 106 sends pointer information Pi (i=
]<) is low P, similarly to the previous time, the corresponding data is retrieved from the disk cache memory 103 based on the new pointer information PI (published in i=) IJ information. The floor ■ protrudes.

However, the data is displayed at the disk device light 30 as before.
will be forwarded to. When the data writing to the disk device 30 is completed, the control unit 106 sets the write flag F' in the corresponding f4 directory information in the directory 104.
At the same time, set the pointer information Pl (+2 to 1) in the directory information to PREGJ 0.
Load into 7. Hereinafter, in the same manner, I ink information Pi
Data Th corresponding to the guy left information linked with
The operation of reading from the f-isk cache memory 103 and writing to the disk device 30 is repeated.

Now, the pointer information PI (1=/) is stored in the PREG 107 in the control unit 106 as shown in the system state diagram of FIG.
Assume that the power to the system is cut off while . When the control unit 106 detects a power outage, the control unit 106 performs the following operations until the power supply voltage drops to a voltage value that no longer guarantees system operation.
6 is loaded into PREG 107 and is indicated by pointer information Pi (1=/) in iL (directory memory 10
4) Directory information such as disk address D
ISK ADR and size information 5 IZE and the disk cache memory address M of the relevant directory information
EM ADR and the data (in the disk cache memory 103) indicated by the size information 5IZE,
In the system state diagram shown in the figure, the data is written to a continuous area of the backup memory 105 starting from the start address, for example, as indicated by the arrow &''-e.Next, the control unit 106 writes to the directory indicated by the pointer information Pi (1=/'). PRE the pointer information P 1 (1=/+1) in the information
After loading into G107, the above-mentioned operation is performed. The control unit 106 performs these operations. Inter information Pl is PI
Starting from the directory information where (i=/), the moromi inter information Pi reaches the directory information indicating the final directory information, 7I? A series of B-REFs linked by interface information Pi) Execute on IJ information (that is, write queue information whose write flag F is logic "1"). The control unit 106 stores the final data all backup memory 1.
05, information indicating that the data is the final data is added to the data.

Next, the operation when the power is restored will be explained. When the power is restored, the control unit 106 accesses the backup memory 105 and sequentially reads out the stored contents starting from the first address.

That is, the control unit 106 selects the disk address DISK A.
DR, then outputs eight pieces of size information 5IZE, and then reads data (to be written to the disk device 30) according to the size information 5IZE. However, the control unit 106
is the data read from the backup memory 105 at the disk address DISK ADH in the disk device 30.
Write to the area indicated by . The control unit 106 repeatedly executes the above-described operation until the final data is reached. As a result, C
The scraped data transferred from the PU 20 is stored in the disk device 3 when the power is restored even though the power has been cut off.
o is stored correctly.

In the above embodiment, the data in the punctured memory 105 (data written to the disk device 3o) was explained as being transferred directly to the disk device 3o, but once it is written to the disk cache memory 103, the data is This is also possible by extracting the KB data and transferring it to the disk device @ao. This is effective when the device interface 1'02 has an input/output control function f111 and is configured to control the data entry by activation from the control unit 106. When writing the shredded data in the backup memory 105 (data written to the disk device 3o) to the disk cache memory 103, the disk address DISK ADR and size information 5IZE added to the data are
In this case, it is easier to create directory information using
s oIc (to be old) data disk device 3
The write operation to o is the same as the normal write operation. 1, the directory information registered in the directory memory 104 makes it possible to extract data from the CPU cache 103 in response to a request from the CPU 2 to extract the data.

By the way, in the above embodiment, the size information 5IZE is included in the directory information, but if the size of the write data is 16", the size information 5IZE is not necessarily necessary.

〔Effect of the invention〕

As detailed above, according to the present invention, when the IE power is turned off,
At least the disk address of the directory information corresponding to the unwritten data on the disk can be saved in backup memory (writable non-volatile memory), so when the power is restored, the contents of the backup memory can be used to access the store and log in. Data can be written to disk correctly. Therefore, compared to the battery backup method, it is necessary to make the device smaller and more vertical.

In addition, the data to be backed up is not all data in the disk storage memory and directory information for all of this data, but data that has not been written to the disk and directory information that corresponds to this unwritten data. It also requires less memory capacity.

[Brief explanation of the drawing]

FIG. 1 is a system state diagram for explaining the entire backup operation when the power is turned off. 10...Disk controller, 2o...CPU
. 30...Disk device, 1OS...Disk cache memory, 104...Directory memory, 105
... Puncture-up memory (rewritable non-volatile memory), 106...ft711 valence 1 copy, 107...
Pointer register (PREG). Applicant's agent Ben Jlli, Suzue Takeshi 9 Figure 1 DISKADRF Pi MEMADR5I
ZE Figure 3

Claims (1)

[Claims] In a disk cache system that adopts a store-through type, there is a disk cache memory that stores data to be written to the disk, and a disk cache memory that stores data to be written to the disk.
Directory information that includes a disk cache memory address that indicates where the data is stored in memory, a disk address that indicates where the data is stored on the disk, and further includes pointer information to the next directory information. , a rewritable nonvolatile memory, a pointer register that holds pointer information to the directory information regarding the address of the disk cache memory to be accessed next, and an I ink register that is used when a power outage is detected. An unloaded file to the disk whose head data is at least the disk address of the directory information in the directory memory specified by and the data in the disk cache memory specified by the disk cache memory address in the directory information. 7', characterized in that it comprises means for writing a repeated data string regarding write data into the non-volatile generation memory, and means for writing the unwritten data to the disk based on the contents of the non-volatile memory after power is restored. Sfcache memory backup method.