JP2000163357A - Scsi switching device and cluster system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an SCSI switching device with which the magnetic disk device of general SCSI standard having no special function for cluster can be applied as a shared magnetic disk device shared from plural computers. SOLUTION: An SCSI switching device 6 is provided while being interposed between server computers 2a-2d and a disk device 7, and equipped with plural input ports for inputting the instruction of SCSI standard transmitted from the server computers 2a-2d and an output port for outputting this instruction of SCSI standard to the disk device 7. Then, the SCSI switching device 6 receives an occupy signal showing the occupancy request of the disk device 7 transmitted from the server computers 2a-2d through an occupy signal line 5 and based on this occupy signal, a changeover switch 61 switches the input port conducted with the output port in the manner of exclusive selection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention makes it possible to apply a general-purpose SCSI standard magnetic disk device having no special function for a cluster as a shared magnetic disk device shared by a plurality of computers. The present invention relates to a SCSI switching device and a cluster system.

[0002]

2. Description of the Related Art In recent years, the spread of computers has been remarkable, and various types of information have been digitized and processed in large amounts by a computer system every day. Also, the demand for the reliability of computer systems is increasing, and various methods for improving the reliability have been devised. One of them is a cluster system.

In this cluster system, a plurality of active and standby computers increase the reliability of the system. For example, as shown in FIG. 3, a server for executing processing required by a client computer 1 is used. A plurality of computers (2a to 2d) are provided, and one of the plurality of server computers is operated as an active system, and the others are set as standby systems. Then, when the server computer operating as the active system fails, one of the other server computers standby as the standby system is switched to the active system to execute the processing requested by the client computer 1. continue.

[0004] As a result, a single failure of the server computer does not cause the system to go down, thereby greatly improving the reliability of the computer system.

[0005]

By the way, in this type of cluster system, a magnetic disk device that can be accessed from a plurality of server computers, such as a shared disk device 3 shown in FIG. 3, is indispensable. The magnetic disk device must recognize a disk occupation command transmitted from the server computer, and have an exclusive control function for validating only access from a specific computer and disabling access from other computers. It has special characteristics. For example, the server computers 2a to 2d and the shared disk device 3 communicate with each other via SCSI (Small Computer System).
m, the shared disk device 3 transmits the SCSI standard disk occupation command (RESERV) transmitted from any server computer.
E command), it is necessary to provide an exclusive function for controlling so that only the access of the server computer which has transmitted this command is enabled. As a result, there is a problem that the shared magnetic disk device becomes very expensive and raises the cost of the cluster system.

The present invention has been made in view of such circumstances, and a shared magnetic disk drive in which a general-purpose SCSI standard magnetic disk drive having no special function for a cluster is shared by a plurality of computers. It is an object of the present invention to provide a SCSI switching device and a cluster system that can be applied as a device.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a method for controlling a plurality of computers to be mounted between a plurality of computers and a SCSI standard magnetic disk drive shared by the plurality of computers. SCS for occupying one of the magnetic disk devices
An occupancy signal transmitting means for transmitting an occupancy signal indicating an occupancy request of the magnetic disk device to the SCSI switching device via a dedicated line in each of the plurality of computers; Transmitted from the plurality of computers
A plurality of input ports for inputting a command of the standard, an output port for outputting a command of the SCSI standard input by the input port to the magnetic disk device, and the magnetic disk transmitted from the plurality of computers Receiving an occupancy signal indicating a device occupancy request via a dedicated line,
A changeover switch for exclusively selecting an input port that is electrically connected to the output port based on the received occupation signal is provided.

According to the present invention, since the exclusive control function can be substituted for the SCSI switching device only by interposing the SCSI switching device, a general-purpose SCSI standard having no special function for the cluster can be used. The magnetic disk device can be applied as a shared magnetic disk device shared by a plurality of computers.

Further, according to the present invention, any one of the plurality of computers occupies the magnetic disk device between a plurality of computers and a SCSI standard magnetic disk device shared by the plurality of computers. An occupation instruction issuing means for issuing an SCSI standard instruction requesting occupation of the magnetic disk device to each of the plurality of computers by interposing a SCSI switching device for causing the SCSI switching device to intervene; , S transmitted from the plurality of computers
A plurality of input ports for inputting CSI standard instructions; an output port for outputting SCSI standard instructions input to the input port to the magnetic disk device; A changeover switch for exclusively selecting an input port that is electrically connected to an output port; and a SCSI standard command requesting the occupation of the magnetic disk drive input to the plurality of input ports, and an input receiving the command. Occupancy recognition means for supplying a control signal for connecting a port to the output port to the changeover switch is provided.

According to the present invention, the occupation of the magnetic disk device can be requested by the SCSI standard command without depending on the output of the occupation signal to the dedicated line. In addition, it is possible to apply a general-purpose SCSI standard magnetic disk device having no special function for a cluster as a shared magnetic disk device shared by a plurality of computers.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) First, a first embodiment of the present invention will be described. FIG. 1 is a diagram showing a schematic configuration of a cluster system according to this embodiment. As shown in FIG. 1, in this client system, four server computers, server computers 2a to 2d, form a cluster. Then, the server computers 2a to 2d
Is a generic SCS without any special features for clusters
The disk device 7 of the I standard is shared.

Therefore, server computers 2a-2
d, the SCSI signal line 4 is led out toward the disk device 7, but the SCSI signal line 4 derived from the server computers 2a to 2d is connected to the SCSI switching device 6 without being connected to the disk device 7. Is done.

The SCSI switching device 6 is for making one of the server computers 2a to 2d occupy the disk device 7, and for inputting a SCSI command transmitted from the server computers 2a to 2d. , And an output port for outputting the SCSI command input from the input port to the disk device 7. And this S
The SCSI signal line 4 is also led out from the CSI switching device 6 toward the disk device 7, and the SCSI signal line 4
Are connected to the disk device 7.

An occupancy signal line 5 for outputting an occupancy signal indicating a request for occupation of the disk device 7 is derived from the server computers 2a to 2d in addition to the SCSI signal line. Also SCSI switching device 6
Connected to. On the other hand, the SCSI switching device 6 includes a switching switch 61 for performing a switching operation so as to exclusively and selectively connect any one of the plurality of input ports to the output port.
The occupation signal transmitted from 2d is supplied to the changeover switch 61. Then, the changeover switch 61 is
Switching is performed based on the supplied occupation signal.

Next, the operation principle of the client system having the above configuration will be described.

Here, first, the server computer 2a
Operates as the active system and executes the processing requested by the client computer, and the other server computers 2b to 2d are on standby as standby systems. Then, a case where the server computer 2b is switched to the active system due to the occurrence of a failure in the server computer 2a is considered.

In this case, as a basic function of the cluster system, the operating environment is taken over from the server computer 2a to the server computer 2b. At this time, the server computer 2b occupies an occupation signal indicating a request to occupy the disk device 7. Output to signal line 5. The output of the occupation signal to the occupation signal line 5 may be executed instead of the cluster software itself, which is the upper software, issuing the SCSI standard disk occupation instruction (RESERVE), or the cluster software may occupy the SCSI standard disk occupation. When an instruction (RESERVE) is issued, the instruction may be converted into an occupation signal output by an operating system or SCSI driver software that accepts the instruction, and then executed.

On the other hand, in the SCSI switching device 6 which has received the occupation signal, the changeover switch 61 executes the switching so as to make the input port connected to the SCSI signal line 4 derived from the server computer 2b and the output port conductive. I do.

That is, in this cluster system, the SCSI switching device 6 is connected to the server computer 2a.
In order to replace the exclusive control function relating to disk access from ~ 2d, a general-purpose disk device 7 can be applied as a shared disk, thereby preventing the cost of the cluster system from increasing.

(Second Embodiment) Next, a second embodiment of the present invention will be described. FIG. 2 is a diagram showing a schematic configuration of the cluster system according to this embodiment. As shown in FIG. 2, in this client system, four server computers, server computers 2a to 2d, form a cluster. Then, the server computers 2a to 2d
Is a generic SCS without any special features for clusters
The disk device 7 of the I standard is shared.

Therefore, the server computers 2a to 2a
d, the SCSI signal line 4 is led out toward the disk device 7, but the SCSI signal line 4 derived from the server computers 2a to 2d is connected to the SCSI switching device 6 without being connected to the disk device 7. Is done.

The SCSI switching device 6 is for occupying one of the server computers 2a to 2d with the disk device 7, and for inputting a SCSI command transmitted from the server computers 2a to 2d. , And an output port for outputting the SCSI command input from the input port to the disk device 7. And this S
The SCSI signal line 4 is also led out from the CSI switching device 6 toward the disk device 7, and the SCSI signal line 4
Are connected to the disk device 7.

The SCSI switching device 6 is provided with a changeover switch 61 for performing a changeover operation so that any one of the plurality of input ports is exclusively and selectively connected to the output port.
Performs switching based on an occupation signal supplied via the occupation signal line 62.

The SCSI switching device 6 includes:
Occupancy recognition device 63 paired with each of a plurality of input ports
a to 63d, and the occupation recognition device 63a
To 63d are SCSI standard disk occupation commands (RESER) transmitted from the server computers 2a to 2d.
VE), and outputs an occupation signal indicating an occupation request of the disk device 7 to the occupation signal line 62. It should be noted that the occupation recognition devices 63a to 63d execute the disk occupation instruction (RESERV
Instructions other than E) are passed to the output port as they are.

Next, the operation principle of the client system having such a configuration will be described.

Here, first, the server computer 2a
Operates as the active system and executes the processing requested by the client computer, and the other server computers 2b to 2d are on standby as standby systems. Then, a case where the server computer 2b is switched to the active system due to the occurrence of a failure in the server computer 2a is considered.

In this case, as a basic function of the cluster system, the operating environment is inherited from the server computer 2a to the server computer 2b. At this time, the server computer 2b uses the cluster software, which is the upper software, to occupy the disk of the SCSI standard. Instruction (R
ESERVE).

On the other hand, in the SCSI switching device 6 which has received the SCSI standard disk occupation command (RESERVE), the occupation recognition device 63b outputs an occupation signal indicating the occupation request of the disk device 7 to the occupation signal line 62. The changeover switch 61 supplied with the occupation signal
Performs switching so that the input port to which the SCSI signal line 4 derived from the server computer 2b is connected and the output port are electrically connected.

That is, in this cluster system, the SCSI switching device 6 is connected to the server computer 2a.
In order to replace the exclusive control function relating to disk access from ~ 2d, a general-purpose disk device 7 can be applied as a shared disk, thereby preventing the cost of the cluster system from increasing. Also, cluster software, which is higher-level software operating on the server computers 2a to 2d, or a SCSI occupation instruction (RES) issued by the cluster software.
ERVE) operating system and S
No modification is made to the CSI driver software or the like.

[0031]

As described in detail above, according to the present invention, only by interposing a SCSI switching device, this S
Since the exclusive control function can be substituted for the CSI switching device, a general-purpose SCSI standard magnetic disk device having no special function for a cluster is applied as a shared magnetic disk device shared by a plurality of computers. It is possible to prevent the cost of the cluster system from increasing.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a cluster system according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of a cluster system according to the second embodiment.

FIG. 3 is a diagram for explaining the specialty of a shared magnetic disk device applied to a conventional cluster system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Client computer 2a-2d ... Server computer 3 ... Shared disk device 4 ... SCSI signal line 5 ... Occupation signal line 6 ... SCSI switching device 7 ... Disk device 61 ... Changeover switch 62 ... Occupation signal line 63a-63d ... Occupation recognition device

Claims (4)

[Claims] An information processing apparatus provided between a plurality of computers and a SCSI standard magnetic disk drive shared by the plurality of computers, for inputting SCSI standard instructions transmitted from the plurality of computers. A plurality of input ports; an output port for outputting a SCSI standard command input from the input port to the magnetic disk device; and an occupancy signal indicating an occupancy request of the magnetic disk device transmitted from the plurality of computers. And a switch for exclusively selecting an input port that is electrically connected to the output port based on the received occupation signal. 2. A computer which is provided between a plurality of computers and a SCSI standard magnetic disk drive shared by the plurality of computers, and which inputs SCSI standard commands transmitted from the plurality of computers. A plurality of input ports, an output port for outputting a SCSI standard command input from the input port to the magnetic disk drive, and an input port electrically connected to the output port based on an externally input control signal. A changeover switch for selectively performing exclusive selection; and recognizing a SCSI standard instruction requesting occupation of the magnetic disk device, which is input to the plurality of input ports, and connecting the input port having input the instruction and the output port. Occupation recognizing means for supplying a control signal for the changeover switch to the changeover switch. SCSI switching device that. 3. A SCSI for allowing any one of the plurality of computers to occupy the magnetic disk device between a plurality of computers and a SCSI standard magnetic disk device shared by the plurality of computers. A switching device interposed, each of the plurality of computers includes an occupation signal transmitting unit that transmits an occupation signal indicating a request for occupation of the magnetic disk device to the SCSI switching device via a dedicated line; A plurality of input ports for inputting SCSI standard instructions transmitted from the plurality of computers; an output port for outputting SCSI standard instructions input by the input port to the magnetic disk device; Indicates an occupancy request of the magnetic disk device transmitted from a plurality of computers A cluster system comprising: a changeover switch that receives an occupation signal via a dedicated line, and exclusively switches an input port that is electrically connected to the output port based on the received occupation signal. 4. An SCSI for allowing one of the plurality of computers to occupy the magnetic disk device between a plurality of computers and a SCSI standard magnetic disk device shared by the plurality of computers. A switching device interposed therebetween, wherein each of the plurality of computers includes an occupation instruction issuing unit that issues an SCSI standard instruction requesting occupation of the magnetic disk device to the SCSI switching device; A plurality of input ports for inputting SCSI standard commands transmitted from the computer, an output port for outputting SCSI standard commands input by the input port to the magnetic disk drive, and an external input Exclusively selects an input port that is electrically connected to the output port based on a control signal. A switch for selectively switching, and for recognizing a SCSI standard command requesting occupation of the magnetic disk device input to the plurality of input ports, and connecting the input port to which the command is input and the output port. And an occupation recognizing means for supplying the control signal to the changeover switch.