JP2001101051A - Magnetic disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain the back-up processing of data held in a magnetic disk without stopping a service. SOLUTION: When access from a host computer 10 is performed during the back-up processing of data held in a magnetic disk 3, the newer data of the magnetic disk 3 or a cache memory 4 are transmitted in response to a request for reading data, and the data are temporarily held in the cache memory 4 in response to a request for writing data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic disk drive having a function of backing up data stored on a disk.

[0002]

2. Description of the Related Art Data stored on a magnetic disk may be in an unreadable state due to a hardware failure, software bug, or the like. Therefore, the data is backed up to another medium such as a magnetic tape or a magneto-optical disk. However, it is necessary to guarantee that data is not updated on the magnetic disk during the backup process. For this reason, conventionally, a method has been employed in which software that may write to a magnetic disk is stopped during backup. It also has two disks,
In the case of a magnetic disk device that employs a method (mirroring) for writing data to both disks and reading data from one of the predetermined disks, a method of separating one disk from the system and performing backup. Was taken.

[0003]

However, in the method of stopping the software during the backup, there is a problem that the software cannot provide the service during the stop, and the time during which the service can be provided is shortened. . In addition, in the method of backing up by detaching one of the mirrored disks from the system, when the detached disk is returned to the magnetic disk device, if the data stored in the other disk does not match, Requires data synchronization,
A heavy load is applied to the apparatus, which may adversely affect other processes. The present invention has been made in order to solve the problems of the conventional magnetic disk device as described above, and eliminates the need for stopping software and synchronizing after the backup process even when backing up data. It is an object of the present invention to provide a magnetic disk device having a backup function.

[0004]

According to the first aspect of the present invention, there is provided a disk for storing data, a storage medium for backing up data stored on the disk, and a method for temporarily storing data. In a magnetic disk drive having a cache memory and a controller, the controller copies data from the disk to the storage medium when a backup process is instructed, and transfers data to the disk during the copy. When receiving the write request, the cache memory stores the data and the address related to the write request. In order to solve the above problem, according to the invention according to claim 2, a disk for holding data, a storage medium for backing up data held on the disk, a cache memory for temporarily holding data, When a backup process is instructed, the controller copies data from the disk to the storage medium, and receives a write request to the disk during the copy. On the basis of the address information included in the write request, data stored in the disk indicated by this address is saved in the cache memory,
Thereafter, the write request is processed.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a magnetic disk drive according to the present invention will be described with reference to the drawings. FIG.
FIG. 1 is a diagram showing an outline of a magnetic disk drive. Reference numeral 1 denotes a magnetic disk drive, in which a controller 2 for controlling the entire apparatus, a magnetic disk 3 for storing data, and read / write data for the magnetic disk 3 are stored. A cache memory 4 for temporarily storing data, a magnetic tape 5 for backing up data stored on the magnetic disk 3,
And a host interface 6 for transmitting and receiving data to and from the host computer 10. The controller 2 and the like are connected via an internal bus 7, and the magnetic disk 2 and the magnetic tape are connected to interfaces 8, 9 respectively.
Is connected to the internal bus 7 via the. Hereinafter, the backup process of the magnetic disk device will be described with reference to the flowchart of FIG. The backup process is started based on an instruction from the host computer 10. When the controller 2 receives an instruction to execute a backup process from the host computer 10 via the host interface 6, the controller 2
First, it is confirmed whether valid data exists in the cache memory 4 (step 1). If valid data exists in the cache memory 4 by this confirmation, the controller 2 writes data from the cache memory 4 to the magnetic tape 5 (step 2).

In the confirmation of step 1, the cache memory 4
If the valid data does not exist or the valid data has already been written to the magnetic tape 5, the data stored on the magnetic disk 3 is backed up (copied) to the magnetic tape 5. Is started (step 3). Thereafter, the controller 2 monitors the end of the backup process (Step 4) and monitors whether there is a write request from the host computer 10 until the end of the backup process is detected (Step 5). When a write request from the host computer 10 is detected in step 5, the controller 2 does not write the data corresponding to the write request to the magnetic disk, but stores the write address and data in the cache memory 4 (step 5). 6). Then, the processing of steps 5 and 6 is continued until the end of the backup processing is detected. Next, in step 4, when the end of the backup processing is detected, the controller 2 writes the unupdated data in the cache memory 4, that is, the write processing of the write request from the host computer 10 to the magnetic disk 3 has not been completed. It is confirmed whether there is completed data (step 7), and if there is no unupdated data, the backup processing is terminated and the magnetic disk device 1 is returned to the normal state.

If it is determined in step 7 that there is unupdated data, the unupdated data is retrieved from the cache memory 4 and a write process is performed on the magnetic disk in accordance with the write address. Write. In this way, the backup processing ends and the operation returns to the normal state. However, even during the backup processing, the magnetic disk is not disconnected, and if a read request is issued from the host computer 10, First, it is checked whether there is data to be hit in the cache memory 4.
In the case of a mishit, data is read from the magnetic disk 3 and transmitted to the host computer 10. In the above description, the backup process is started based on an instruction from the host computer 10. However, as shown in FIG. 3, for example, a switch (or a timer) 11 is provided in the main body of the magnetic disk device 1, and The backup process may be started based on the operation of the switch 11. Also, a magnetic tape has been described as an example of a device for holding data to be copied.
O) or a magnetic disk.

As described above, in the magnetic disk drive of the present invention, the service is not stopped even during the data backup process, and the write request during the backup process is held in the temporary cache memory. By waiting for writing to the magnetic disk, it is possible to prevent a mismatch between the data on the magnetic disk at the start of the backup process and the data backed up on the magnetic tape due to a write request generated during the backup process. I can do it. Next, another embodiment of the present invention will be described. In this embodiment, since the configuration of the magnetic disk drive is the same as that of FIG. 1, only the operation will be described with reference to the flowchart of FIG. 4, and the description of the configuration will be omitted. When receiving an instruction to execute backup processing from the host computer 10 via the host interface 6, the controller 2 first checks whether valid data exists in the cache memory 4 (step 11). If valid data exists in the cache memory 4 by this confirmation, the controller 2 writes data from the cache memory 4 to the magnetic tape 5 (step 12). If there is no valid data in the cache memory 4 or if the valid data has already been written to the magnetic tape 5 in the confirmation of step 11, the magnetic data of the data stored on the magnetic disk 3 is A backup (copy) process to the tape 5 is started (step 13). Thereafter, the controller 2 monitors the end of the backup process (Step 14), and continues until the end of the backup process is detected.
Monitor whether there is a write request from 0 (step 1)
5).

In step 15, when a write request from the host computer 10 is detected, data write processing is performed on the magnetic disk 3. At this time, the overwritten data and the address where the data was stored are stored. It is saved in the cache memory 4 (step 16). The processing of steps 15 and 16 is continued until the end of the backup processing is detected. When the end of the backup process is detected in step 14, the controller 2
Writes the data saved in the cache memory 4 during the backup processing to the magnetic tape 5 to end the backup processing, and returns the magnetic disk device 1 to the normal state. In this way, the backup processing ends and the operation returns to the normal state. However, even during the backup processing, the magnetic disk is not disconnected, and if a read request is issued from the host computer 10, The data is read from the magnetic disk 3 and transmitted to the host computer 10. As described above, in the magnetic disk device of the present invention, the data to be overwritten is saved in the temporary cache memory without interruption of the service, and even when a write request during the backup process is met, the backup process is performed. By writing the data on the magnetic tape 5 after the end, it is possible to prevent the data on the magnetic disk at the start of the backup processing from being inconsistent with the data backed up on the magnetic tape.

Although the above description has been made on the basis of a system including one host computer and a magnetic disk device, a system in which a plurality of host computers share one magnetic disk device is also conceivable. In such a system, when write requests from a plurality of host computers are accepted, there is a possibility that the validity of data in the cache memory or the magnetic disk may not be maintained. It is better to control so that write permission is given to only one host computer and read-only is allowed to other host computers.

[0011]

As described above, according to the present invention,
Even when backing up data on a magnetic disk that is normally accessed by the host computer, backup processing can be performed without stopping services.

[Brief description of the drawings]

FIG. 1 is a diagram showing a magnetic disk device having a backup function according to the present invention.

FIG. 2 is a flowchart illustrating a backup process according to the present invention.

FIG. 3 is a diagram showing another configuration of the magnetic disk device having a backup function of the present invention.

FIG. 4 is a diagram showing another configuration of the magnetic disk device having a backup function of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Magnetic disk device 2 ... Controller 3 ... Magnetic disk 4 ... Cache memory 5 ... Magnetic tape

Claims (2)

[Claims] 1. A disk for holding data, a storage medium for backing up data held on the disk, a cache memory for temporarily holding data,
In a magnetic disk device having a controller, when a backup process is instructed, the controller copies data from the disk to the storage medium, and receives a write request to the disk during the copy. A magnetic disk drive wherein data and an address relating to a write request are stored in the cache memory. 2. A disk for holding data, a storage medium for backing up data held on the disk, a cache memory for temporarily holding data,
In a magnetic disk device having a controller, when a backup process is instructed, the controller copies data from the disk to the storage medium, and upon receiving a write request to the disk during the copy, A magnetic disk drive characterized in that, based on address information included in a write request, data stored on the disk indicated by the address is saved in the cache memory, and thereafter the write request is processed.