Electrical computers and digital data processing systems: input/ – Input/output data processing – Peripheral adapting
Reexamination Certificate
2000-06-15
2003-03-04
Gaffin, Jeffrey (Department: 2182)
Electrical computers and digital data processing systems: input/
Input/output data processing
Peripheral adapting
C710S020000, C710S036000, C710S038000, C709S200000, C709S201000, C709S202000, C709S203000, C709S213000, C709S214000, C709S216000, C709S217000, C709S218000, C709S219000, C709S246000, C711S100000, C711S111000, C711S161000, C711S162000, C711S200000, C714S779000
Reexamination Certificate
active
06529976
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a heterogeneous computer system comprising a host computer and a plurality of I/O subsystems, and more in particular to a method for making it possible to back up the data stored in a memory between a host computer and an I/O subsystem which cannot be directly connected due to the difference in access interface, and a heterogeneous computer system including a plurality of I/O subsystems having different access interfaces connected to the system and the host computer.
In mainframes, a large scale of memory hierarchy (storage hierarchy) including a combination of a plurality of external memories having different processing speeds and different storage capacities is accompanied by a satisfactory data management function and an overall storage management function intended to support an optimum data arrangement and an efficient operation. The IBM's DFSMS (Data Facility Storage Management Subsystem) is an example, which is described in detail in “IBM SYSTEMS JOURNAL, Vol. 28, No. 1, 1989, pp.77-103.
The disk data of the I/O subsystem of the mainframe computer system having the above-mentioned management function can be backed up in a medium such as a magnetic tape or a magnetic tape library capable of storing a large quantity of data with a low cost per bit.
An open system such as a personal computer or a work station, unlike the mainframe, is not equipped with a magnetic tape or a magnetic tape library capable of storing a large quantity of data.
Generally, in an open system such as a personal computer or a work station, a disk is accessed in accordance with a fixed-length record format, while the mainframe accesses a disk in accordance with a variable-length record format called the count key data format.
As a result, the disk subsystem for the mainframe computer is often configured independently of the disk subsystem for the open system.
On the other hand, a technique for transmitting and receiving data between I/O subsystems is disclosed in U.S. Pat. No. 5,155,845.
In a disk subsystem for an open system and a disk subsystem for a mainframe computer which use different host computers, the back-up and other functions are independently operated and managed.
In view of the fact that the open system lacks medium such as a magnetic tape or a magnetic tape library capable of storing a larger quantity of data, as described above, it is effective to back up the data in the I/O subsystem of the mainframe.
An ordinary disk system for the open system, however, cannot be connected directly to the mainframe due to the difference in the interface thereof.
U.S. Pat. No. 5,155,845 fails to disclose how to process the read/write operation for a storage system not directly connected to a host computer.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method and a system for backing up data stored in a memory between a host computer and an I/O subsystem that cannot be connected directly to each other due to the difference in access interface.
Specifically, an object of the invention is to provide a method and a system for backing up data stored in an I/O subsystem of an open system from a mainframe not directly connected to the I/O subsystem.
Another object of the invention is to provide a method and a computer system in which a mainframe is capable of accessing a memory of an I/O subsystem of an open system not directly connected to the mainframe.
Still another object of the invention is to provide a system and a method of access in which two or more I/O subsystems having different interfaces can be connected to a mainframe.
In order to achieve the above-mentioned objects, according to one aspect of the present invention, there is provided a heterogeneous computer system comprising a first host computer, a first I/O subsystem directly connected to the first host computer by an interface of variable-length record format and including at least one external memory, a second host computer, a second I/O subsystem directly connected to the second host computer by an interface of fixed-length record format and including at least one external memory, and a communication unit for connecting the first I/O subsystem to the second I/O subsystem;
wherein the first I/O subsystem includes a table for storing a device address of an external memory, data indicating one of the external memory of the first I/O subsystem and the external memory of the second I/O subsystem to which the device address is assigned, and a device address of the external memory in the second I/O subsystem when the device address is assigned to the external memory of the second I/O subsystem; and
wherein upon receipt of a read/write request conforming to the interface of variable-length record format from the first host computer and including an address of an external memory to be read from or written into, and upon decision, with reference to the table, that the external memory address included in the read/write request is assigned to the external memory included in the second I/O subsystem, the first I/O subsystem converts the read/write request into a second read/write request conforming to the interface of fixed-length record format and sends the second read/write request to the second I/O subsystem.
According to another aspect of the invention, there is provided a heterogeneous computer system comprising a first host computer, a first I/O subsystem directly connected to the first host computer by an interface of variable-length record format and including at least one external memory, a back-up system connected to the first host computer, a second host computer, a second I/O subsystem directly connected to the second host computer by an interface of fixed-length record format and including at least one external memory, and a communication unit for connecting the first I/O subsystem to the second I/O subsystems;
wherein the first host computer includes a means for issuing to the first I/O subsystem a read request conforming to the interface of variable-length record format and containing the address of an external memory from which data is to be read, and backing up the data received from the first I/O subsystem into the back-up system;
wherein the first I/O subsystem includes a table for storing the device address of an external memory, data indicating that one of the external memory of the first and the second I/O subsystems to which the device address is assigned, and the device address of the external memory in the second I/O subsystem when the first device address is assigned to the external memory of the second I/O subsystem; and
wherein upon receipt from the first host computer of a read request conforming to the interface of variable-length record format including an external memory address to be read, and upon decision, with reference to the above-mentioned table, that the device address of the memory address included in the read request is assigned to the external memory included in the second I/O subsystem, the first I/O subsystem converts the read request into a second read request conforming to fixed-length interface and sends the second read request to the second I/O subsystem while at the same time sending to the first host computer the data received from the second I/O subsystem.
According to still another aspect of the invention, there is provided a heterogeneous computer system comprising a first host computer, a first I/O subsystem directly connected to the first host computer by an interface of variable-length record format and including at least one external memory, a back-up system connected to the first host computer, a second host computer, a second I/O subsystem directly connected to the second host computer by an interface of fixed-length record format and including at least one external memory, and a communication unit for connecting the first I/O subsystem to the second I/O subsystem;
wherein the first host computer includes a means for issuing to the first I/O subsystem a write request conforming to the interface of
Fukuzawa Yasuko
Nakano Toshio
Yamamoto Akira
Antonelli Terry Stout & Kraus LLP
Gaffin Jeffrey
Hitachi , Ltd.
Nguyen Tanh
LandOfFree
Heterogeneous computer system, heterogeneous input output... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Heterogeneous computer system, heterogeneous input output..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Heterogeneous computer system, heterogeneous input output... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3011508