JPH10222309A - Auxiliary storage device adaptive to scsi buses - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable other equipment to use a SCSI bus even if the SCSI bus needs to be occupied by one auxiliary storage device and specific SCSI equipment by constituting a connecting means so that it can be connected to SCSI buses each connecting with a host. SOLUTION: Two SCSI buses 20A and 20B to which host PCs(personal computer) 21A and 21B are connected to one auxiliary storage device 10. Then the 1st host PC 21A and storage devices 22A to 22A are connected to one SCSI bus 20A and the 2nd host PC 21B and auxiliary storage device 10 are connected to the other SCSI bus 20B. Therefore, data in the auxiliary storage device 10 can be accessed through both the SCSI buses 20A and 20B without any physical equipment constitution alteration. Consequently, the use ranges of the SCSI buses 20A and 20B can be expanded and the reliability of the system is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to an auxiliary storage device which enables simultaneous connection to a plurality of SCSI buses each having a host connected to the bus.

[0002]

2. Description of the Related Art A conventional auxiliary storage device has a single system SCS.
Only one I bus (one bus connected by a SCSI interface device) can be connected, and a plurality of SCSs can be connected.
It could not be connected to the I bus at the same time. Therefore, when it becomes necessary for a set of SCSI devices to occupy the bus, other devices connected to the SCSI bus of that system cannot access each other. Also, the conventional SCSI interface device is a SCSI interface device.
Due to the limitations of the standard, only a maximum of seven auxiliary storage devices can be connected to one SCSI bus.

[0003]

As described in the prior art, the conventional auxiliary storage device can be connected to only one SCSI bus, and at the same time, can be accessed by only one auxiliary storage device. Is possible. Therefore, one set of S
When a bus is occupied by a CSI device (for example, a host or a CD-ROM server and an auxiliary storage device), there is a problem that other devices connected to the same SCSI bus cannot be accessed. When data is shared and used by a plurality of SCSI buses, it is necessary to physically move using a removable medium or physically reconnect the SCSI device itself. Furthermore, one system S
When a plurality of host adapters exist on the CSI bus, if data is transferred to one auxiliary storage device and another host adapter accesses it, correct data may not be transferred or data may be destroyed. May occur.

According to the present invention, even when one auxiliary storage device and a specific SCSI device need to occupy the SCSI bus, other devices can use the SCSI bus, and the SCSI bus usage range is increased. First to expand
Subject. Further, even when data is shared and used by a plurality of SCSI buses, the physical movement of the removable medium and the physical connection operation of the SCSI device are reduced as much as possible to improve the operability. That second
Subject. Further, it is a third object to improve the reliability of the system by maintaining the data being transferred even when another access request occurs during the data transfer to one auxiliary storage device. And

[0005]

According to the first aspect of the present invention, S
In an auxiliary storage device provided with connection means for connecting to a CSI bus, the connection means is configured to be connectable to a plurality of SCSI buses each having a host connected to one SCSI bus.

According to a second aspect of the present invention, in the auxiliary storage device of the first aspect, a control means for controlling simultaneous access from a plurality of SCSI buses is provided.

According to a third aspect of the present invention, in the auxiliary storage device of the first aspect, a bus selecting means for selecting a SCSI bus to respond to is provided.

According to a fourth aspect of the present invention, in the auxiliary storage device according to any one of the first to third aspects, a detecting means for detecting a data transfer break is provided.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a plurality of SCSI bus compatible auxiliary storage devices of the present invention (hereinafter referred to as auxiliary storage devices of the present invention) will be described in detail with reference to the drawings. According to the present invention, in order to connect an auxiliary storage device, for example, an HDD, a MOD, or another media drive to a plurality of SCSI buses, each SCSI
The feature is that a controller for controlling connection with the bus is added.

FIG. 1 is a block diagram showing an example of an embodiment of a main configuration of an auxiliary storage device compatible with a plurality of SCSI buses according to the present invention. In the figure, 10 is an auxiliary storage device, 1 is a storage device unit, 2 is a controller, 3
a and 3b show the first and second SCSI adapters.

As shown in FIG. 1, the auxiliary storage device 1
0, in addition to the storage unit 1, first and second SCSI adapters 3a and 3b, and a controller 2 for controlling these
Are added. FIG. 1 shows two SCs.
Although only the SI adapter is shown, it is also possible to provide three or more SCSI adapters. First and second SCS
The I adapters 3a and 3b have a function of connecting to the SCSI bus. For this purpose, the controller 2 has the following functions. First, each SCS
It has a function of setting a SCSI-ID for the I bus (the first and second aspects of the invention).

Second, when the auxiliary storage device 10 needs to be occupied by one SCSI bus, it is possible to set a SCSI bus to which a response is to be returned (claims 2 and 3). 3 invention). This setting is performed by a vendor-unique (Vender Unique) SCSI command or a hardware switch. At this time, even if there is an access request to a SCSI bus that is not targeted, the controller 2 controls the SCSI bus. In the control in this case, in response to the access request, a busy status (busy status), a check condition (Not Ready), or the like is returned, or the request (Selection) is returned.
The response is made by a method that does not respond to the request.

Third, in order to prevent a malfunction due to a change in signal level, the state of the SCSI adapters 3a and 3b that are not connected to the SCSI bus during the actual operation is detected and automatically or manually operated ( It also has a function to guarantee the signal level by prompting (informing by message display or the like) (the inventions of claims 2 and 3). Fourth, when a new access request to the same data occurs during data transfer to the auxiliary storage device,
In order to avoid destruction of data and confusion of the system caused by responding to the access request, the controller 2 has a function of restricting the access request (claim 4). For this purpose, the data being transferred is detected in units of files instead of in units of SCSI commands, and the timing of bus switching is controlled by the boundaries. Next, a system using the auxiliary storage device of the present invention will be described.

FIG. 2 is a functional block diagram showing an example of the configuration of an embodiment of a SCSI system using the auxiliary storage device of the present invention. In the figure, 10 is an auxiliary storage device similar to that of FIG. 1, 20A is a first SCSI bus, 2
1A is a first host PC, 22A to 24A are storage devices,
20B is a second SCSI bus, 21B is a second host P
C is shown.

FIG. 2 shows one auxiliary storage device 10.
And a host PC (personal computer) 2
SCSI bus 20 to which two systems 1A and 21B are connected
A and 20B are connected. A first host PC 21A and a plurality of storage devices 22A to 24A are connected to one first SCSI bus 20A. Also, the other second SCSI bus 20B
Is connected to the second host PC 21B and the auxiliary storage device 10 (other storage devices are omitted to simplify the drawing). Therefore, the data in the auxiliary storage device 10 can be accessed from both the first and second SCSI buses 20A and 20B without changing the physical device configuration.

In this state, if the first host PC 21A and the storage device 22 are connected between the first SCSI bus 20A.
A device such as one of A to 24A is a first SCS
Even if the I-bus 20A is occupied, the second SCSI bus 2
0B, for example, the second host PC 2
1B and the auxiliary storage device 10 are connected to the second SCSI bus 20
B can transmit and receive data. In this case, even if the first host PC 21A and the auxiliary storage device 10 occupy the first SCSI bus 20A between the first SCSI buses 20A, the second host PC 21B
It is possible to access the auxiliary storage device 10 through the second SCSI bus 20B. Here, an operation when a connection request is made from the SCSI bus is shown in a flow chart.

FIG. 3 is a flowchart showing the flow of main processing when a connection request is made from the SCSI bus in a system using the auxiliary storage device of the present invention. In the figure, # 1 to # 6 indicate steps.

In step # 1, when a data transfer request is received through the SCSI bus, in the next step # 2, another S
It is checked whether the CSI bus occupies the auxiliary storage device 10 (the invention of claim 2). As a result of the check in step # 2, when another SCSI bus occupies the auxiliary storage device 10, the process proceeds to step # 6. Step #
At 6, the transfer request is set as an access restriction target, and the flow of FIG. 3 ends. If another SCSI bus does not occupy the auxiliary storage device 10, step # 3
To check whether data is being received from another SCSI bus (the invention of claim 3).

As a result of checking in step # 3, another S
If data is being received from the CSI bus, step #
In step 4, it is checked whether or not the immediately preceding data transfer break is a file-based break.
If it is not a file-unit delimiter, the process proceeds to step # 6, and the transfer request is set as an access-restricted target, and the flow of FIG. Also, as a result of the determination in the previous step # 4, the delimiter of the immediately preceding data transfer is
If it is a file unit break, go to step # 5,
The flow is connected to the SCSI bus that has made the transfer request, and the flow of FIG. 3 ends. On the other hand, as a result of the determination in the previous step # 3, even when data is not being received from another SCSI bus, the process proceeds to step # 5, and similarly, the data is connected to the SCSI bus that has made the transfer request. Then, the flow of FIG. 3 ends.

[0020]

In the auxiliary storage device according to the first aspect, the connection means is configured to be connectable to a plurality of SCSI buses each having a host connected to one SCSI bus. Therefore, it is possible to simultaneously connect to a plurality of SCSI buses, and even when a specific SCSI device needs to occupy the SCSI bus, other devices can use the SCSI bus. It is enlarged.

According to a second aspect of the present invention, in the auxiliary storage device of the first aspect, simultaneous access from a plurality of SCSI buses can be controlled. Therefore, when there is simultaneous access from a plurality of connected SCSI buses, control corresponding to the simultaneous access becomes possible, and physical movement of removable media and physical connection operations of SCSI devices are reduced as much as possible. Therefore, the operability is improved.

According to a third aspect of the present invention, in the auxiliary storage device of the first aspect, a SCSI bus which responds can be selected. Therefore, a plurality of connected SCs
A SCSI bus responding from the SI bus can be selected, and the same effect as that of the auxiliary storage device of the second aspect can be obtained.

According to a fourth aspect of the present invention, there is provided the auxiliary storage device according to any one of the first to third aspects, further comprising means for detecting a data transfer break. Therefore, S
Since it becomes possible to detect a break in data transferred through the CSI bus, it is possible to avoid inconveniences such as incorrect data transfer and data destruction.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of an embodiment of a main configuration of an auxiliary storage device compatible with a plurality of SCSI buses of the present invention.

FIG. 2 is a functional block diagram showing a configuration example of an embodiment of a SCSI system using an auxiliary storage device according to the present invention;

FIG. 3 is a flowchart showing a flow of main processing when a connection request is made from a SCSI bus in a system using the auxiliary storage device of the present invention.

[Explanation of symbols]

Reference Signs List 10 auxiliary storage device, 1 storage device unit, 2 controllers, 3a and 3b first and second SCSI adapters, 20
A first SCSI bus, 21A first host PC,
22A to 24A storage device, 20B second SCSI bus, 21B second host PC

Claims (4)

[Claims] 1. An auxiliary storage device having connection means for connecting to a SCSI bus, wherein said connection means is configured to be connectable to a plurality of SCSI buses each having a host connected to one SCSI bus. Characteristic auxiliary storage device. 2. The auxiliary storage device according to claim 1, further comprising control means for controlling simultaneous access from a plurality of SCSI buses. 3. The auxiliary storage device according to claim 1, further comprising bus selection means for selecting a SCSI bus to respond to. 4. The auxiliary storage device according to claim 1, further comprising detection means for detecting a data transfer break.