JPH0793101A - Data backup device - Google Patents

Abstract

PURPOSE:To perform the backup of data without applying any load to a host computer in a computer system connected by an SCSI bus by reading reloaded data and writing them in a backup storage device in a state that the host computer does not use the bus. CONSTITUTION:A host computer 2 is connected through an SCSI bus 4 to a storage device 6 such as a hard disk, backup storage device 8 such as an optical disk and the backup device 10. The host computer 2 writes or reads data through the SCSI bus 4 in or from the storage device 6. From the change of the signal of the SCSI bus 4 at that time, the backup device 10 decodes which area data of the storage device 6 have been decoded by the host computer 2, and performs backup processing by reading the data from the storage device 6 and writing the read data in the backup storage device 8 while utilizing the idle time of the SCSI bus 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data backup device for backing up data written by a computer in a storage device such as a hard disk to another storage device.

[0002]

2. Description of the Related Art A host computer normally uses a hard disk drive as a storage device next to a main memory for recording and reading a large amount of data. As a backup storage device of relatively slow but removable capacity in case the data on the hard disk drive is destroyed by a device failure or operation error, or to transfer the stored contents to another host computer Optical disk devices and magnetic tape devices are used.

The data backup work in such a system has conventionally been carried out by the host computer repeatedly reading data from the storage device and writing the data in the backup storage device.

This will be described in detail with reference to the drawings.

In FIG. 1, a read command is sent from the host computer 2 to the storage device 6 via the SCSI bus 4, whereby data is transferred from the storage device 6 to the host computer 2.

Next, referring to FIG. 2, the backup storage device 8 from the host computer 2 via the SCSI bus 4.
To the backup storage device 8 by the write command.

Data in the storage device 6 is transferred to the backup storage device 8 by repeating the operations shown in FIGS. 1 and 2 as many times as necessary.

[0008]

However, in the data backup processing performed by the host computer, there is a problem that the host computer is occupied for the work during the data backup work, and other work cannot be performed.

Further, since the data transfer rate of the backup storage device is low, there is a problem that the system must be stopped for a long time depending on the amount of data to be backed up.

For this reason, there are cases where backup cannot be carried out even if it is necessary.

The present invention has been made to solve the above-mentioned conventional problems. When the data on the storage device is changed regardless of whether the host computer is operating or stopped, the backup operation is performed at any time. It is an object of the present invention to provide a data backup device that starts data backup and backs up data on a storage device without imposing a load on a host computer.

[0012]

The present invention provides a data backup device of a system comprising a host computer connected by a bus defined by the SCSI standard, a storage device such as a hard disk, and a backup storage device such as an optical disk. , Means for monitoring and detecting a bus sequence, which is a procedure for exchanging signals between the host computer and the storage device on the SCSI bus, means for recording the bus sequence, and the host computer from the bus sequence recording A means for decoding the area information in which the data is rewritten, a means for detecting a bus idle in which the host computer does not use the SCSI bus, and a data read / write operation for the storage device and the backup storage device. Means for issuing commands, and After the idle is detected, a unit for issuing a read command to the storage device, based on the area information of the storage device rewritten by the host computer, which is obtained by the decoding unit, and performing a control for writing to the backup storage device And a daisy chain connection to the SCSI bus to which the host computer and the storage device are connected.

[0013]

According to the present invention, by monitoring the exchange of signals between the host computer and the storage device on the SCSI bus, it is recognized that the host computer has rewritten data in an area of the storage device, The load is applied to the host computer by issuing a read command to the storage device to read the rewritten data and issuing a write command to the backup storage device to write the read data while the computer is not using the bus. Enables you to perform backup processing without calling.

Further, since this processing is processed whenever the rewriting by the host computer occurs, the time for backup after the processing as in the conventional case becomes unnecessary.

[0015]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 3 is a block diagram showing a connection state on the SCSI bus of this embodiment.

First, the rough operation of this embodiment will be described with reference to FIG.

In FIG. 3, the host computer 2 is S
A storage device 6 such as a hard disk, a backup storage device 8 such as an optical disk, and a backup device 10 are connected via a CSI bus 4. The host computer 2 writes or reads data in the storage device 6 via the SCSI bus 4. The backup device 10 decodes which area of the storage device 6 the data has been rewritten by the host computer 2 from the change in the signal of the SCSI bus 4 at this time, and uses the idle time of the SCSI bus 4 to transfer the data from the storage device 6. Backup processing is performed by reading and writing the read data to the backup storage device 8.

The internal configuration of the backup device 10 of this embodiment is as shown in FIG.
It is connected to an SI device and is connected to a SCSI bus sequence monitoring circuit 12 and a SCSI command issuing circuit 14 for monitoring the bus status. The SCSI bus sequence monitoring circuit 12 includes a bus sequence storage circuit 16 and a control CPU 1.
8 is connected. Also, the SCSI command issuing circuit 1
4 is connected to the control CPU 18 and the data buffer 20.

The SCSI bus sequence monitoring circuit 12 uses S
The state of the CSI bus 4 is detected, this data is stored in the bus sequence storage circuit 16, and the control CPU 18
It is used for detection of bus idle by the timer and processing program built in. Further, the SCSI command issuing circuit 14 issues a data read command and a data write command to a SCSI device connected to the SCSI bus 4 according to an instruction from the control CPU 18, and temporarily stores the data at this time in the data buffer 20. To store.

Next, the backup processing of this embodiment will be described in detail with reference to block diagrams showing the flow of commands and data, FIGS. 4 to 6, a flowchart showing the backup procedure, and FIG.

First, referring to FIG. 4, the backup device 1
0 means that when the host computer 2 writes data to the storage device 6 via the SCSI bus 4, S at that time is written.
The bus sequence is fetched from the signal of the CSI bus 4 and is stored in the bus sequence storage circuit (see FIG.
16).

Here, in step 100 of the flowchart of FIG. 7, it is determined whether or not all rewritten data has been backed up. If all are backed up, the process goes to step 102 to end the process.

If the backup is not completed yet,
Going to the next step 104, the control CPU 18 in the backup device 10 makes the SCSI bus sequence monitoring circuit 12
Via, confirm that the SCSI bus 4 has not been used by the host computer 2 for a certain period of time.

If the SCSI bus is idle for a certain period of time, the process proceeds to the next step 106 to execute the backup process.

In step 106, as shown in FIG. 5, a read command is sent from the backup device 10 to the storage device 6 via the SCSI bus 4, whereby the storage device 6 transfers data to the data buffer 20 in the backup device 10. Is transferred.

Next, in step 108, as shown in FIG. 6, a write command is sent from the backup device 10 to the backup storage device 8 via the SCSI bus 4, whereby the backup device 10 sends data to the backup storage device 8. Is transferred.

Data in the storage device 6 is transferred to the backup storage device 8 by repeating the processing of steps 106 and 108 as many times as necessary.

FIG. 8 shows an operation timing chart of the data backup device when no command is input from the host during the backup process. FIG. 9 shows an operation timing chart of the data backup device when a command is input from the host during the backup process.

While this processing is being performed, the host computer 2 is not occupied by this work and can perform other processing. Further, the backup process is performed whenever data is written to the storage device 6, so that there is no need for an operation for backup, and since the bus idle time is used, the processing time required for backup does not appear in the table. .

[0031]

As described above, according to the present invention, data in a storage device such as a hard disk can be backed up to a backup storage device such as an optical disk without imposing a load on the host computer, and the bus idle time can be effectively used. This has the effect that the total processing time can be shortened.

[Brief description of drawings]

FIG. 1 is a block diagram showing a conventional procedure for backing up using a host computer.

FIG. 2 is a block diagram showing a conventional procedure for backing up using a host computer.

FIG. 3 is a block diagram showing a connection state on the SCSI bus of the present invention.

FIG. 4 is a block diagram showing a procedure for backing up using the present invention.

FIG. 5 is a block diagram showing a procedure for backing up using the present invention.

FIG. 6 is a block diagram showing a procedure for performing backup using the present invention.

FIG. 7 is a flow chart showing a procedure for backing up using the present invention.

FIG. 8 is a timing chart when a command from the host is not input during backup processing.

FIG. 9 is a timing chart when a command from the host is input during backup processing.

[Explanation of symbols]

 2 ... Host computer 4 ... SCSI bus 6 ... Storage device 8 ... Backup storage device 10 ... Backup device 12 ... SCSI bus sequence monitoring circuit 14 ... SCSI command issuing circuit 16 ... Bus sequence storage circuit 18 ... Control CPU 20 ... Data buffer

Claims (1)

[Claims] 1. A data backup device for a system comprising a host computer connected by a bus defined by the SCSI standard, a storage device such as a hard disk, and a backup storage device such as an optical disk, and a host computer on the SCSI bus. Means for monitoring and detecting a bus sequence, which is a procedure for exchanging signals with a storage device, means for recording the bus sequence, and decoding area information in which the host computer rewrites data in the storage device from the bus sequence recording. Means, a means for detecting a bus idle in which the host computer does not use the SCSI bus, a means for issuing commands such as data read / write to the storage device and the backup storage device, After the bus idle is detected, A read command is issued to the storage device on the basis of the area information of the storage device rewritten by the host computer obtained by the code means, and a write command is written to the backup storage device. The SC in which the host computer and the storage device are connected
A data backup device characterized by being connected to an SI bus in a daisy chain.