Electrical computers and digital processing systems: multicomput – Master/slave computer controlling – Master accessing slave storage
Reexamination Certificate
1998-05-28
2001-06-12
Rinehart, Mark H. (Department: 2152)
Electrical computers and digital processing systems: multicomput
Master/slave computer controlling
Master accessing slave storage
C709S216000
Reexamination Certificate
active
06247046
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to a method and apparatus for interfacing two remotely disposed devices over a transmission medium capable of transmitting data over long distances. The invention may be used, for example, to interface a master storage device of a host CPU to a remotely disposed mirroring storage device, particularly where the master storage device communicates with its host CPU using the ESCON protocol.
BACKGROUND OF THE INVENTION
ESCON is a standard computer system interface and protocol developed by International Business Machines (IBM). ESCON is applicable to an environment such as the one shown in
FIG. 1
, in which a central processing unit (CPU)
1
is coupled to a channel
3
having direct access to a main memory (not shown) of the CPU. The channel provides input/output capability to the CPU. More particularly, the channel
3
is coupled, over a link
5
, to one or more control units
7
, which each is in turn coupled to a plurality of I/O peripherals
9
. Control unit
7
controls access to CPU
1
, via channel
3
, for each of the I/O peripherals
9
, allowing each to have direct access to the CPU memory.
ESCON defines the interface and protocol for communicating over link
5
between channel
3
and control unit
7
, and is described in detail, for example, in “ENTERPRISE SYSTEMS ARCHITECTURE/390—ESCON I/O INTERFACE”, Third Edition (1992) published by IBM, which is incorporated herein by reference. Dedicated ESCON links have been provided so that control unit
7
, along with its associated I/O peripherals
9
, can be disposed at a location somewhat remote from CPU
1
and channel
3
. However, these dedicated links have conventionally been limited to relatively short distances. For example, IBM states that its dedicated ESCON links are limited to approximately 60 km. Although this number may be conservative, it is believed that conventional dedicated ESCON links are limited to distances of approximately 80 km and less.
Conventional dedicated ESCON links between a channel and control unit suffer from two significant disadvantages. First, the above-described limit on the maximum supported distance may be insufficient for some applications. Second, it is often costly to implement these dedicated links because they are not part of a public communication network, and may not be capable of being implemented over pre-existing communication lines.
It is an object of the present invention to provide an improved interface for enabling communication between two remotely disposed devices, including ESCON compatible devices.
SUMMARY OF THE INVENTION
In accordance with one illustrative embodiment of the invention, a computer system is provided comprising a central processing unit (CPU), a first storage system that is coupled to the CPU so that the CPU can store information in the first storage system, a second storage system, and a communication link coupling the second storage system to the CPU so that the CPU can store information in the second storage system, the communication link comprising a data communication line operable within a public communication network and which are available from common carriers such as AT&T, MCI, Sprint, etcetera.
In another illustrative embodiment of the invention, a computer system is provided comprising a CPU, a first storage system that is coupled to the CPU so that the CPU can store information in the first storage system, means for establishing communication between the CPU and the first storage system in accordance with the ESCON protocol, a second storage system, and a communication link coupling the second storage system to the CPU so that the CPU can store information in the second storage system, the communication link having a distance greater than 80 km.
In another illustrative embodiment of the invention, a computer system is provided comprising a CPU, a first storage system that is coupled to the CPU so that the CPU can store information in the first storage system, means for establishing communication between the CPU and the first storage system in accordance with the ESCON protocol, a second storage system, a communication link coupling the first and second storage systems, and means for establishing communication between the first and second storage systems over the communication link in accordance with a communication protocol having fewer transactions per operation than the ESCON protocol.
In a further illustrative embodiment of the invention, a method of protecting against a loss of the data stored in the first storage system of a computer system including a CPU coupled to the first storage system is provided. The method includes the steps of: (A) disposing a second storage system at a location remote from a location of the first storage system; (B) coupling the second storage system to the first storage system with a data communication line selected from the family of public network carriers as T-carriers; (C) communicating the at least some of the data stored in the first storage system over the data line from the first storage system to the second storage system; and (D) storing the at least some of the data communicated over the data line in the second storage system so that the second storage system mirrors the at least some of the data stored in the first storage system.
In a further illustrative embodiment of the invention, a method is provided for communicating data frames from a first device to a second device over a data link coupling the first and second devices, the second device including a storage buffer capable of simultaneously storing no more than N data frames received over the data link from the first device. The method includes the steps of: (A) transmitting a request from the second device to the first device requesting that a number of data frames greater than N be transferred from the first device to the second device; and (B) receiving all of the number of requested data frames from the first device in a single data transmission.
In yet another illustrative embodiment of the invention, a method is provided for communicating data frames from a first device to a second device over a data link coupling the first and second devices, the second device including a storage buffer capable of simultaneously storing no more than N data frames received over the data link from the first device. The method includes the step of (A) transmitting a number of data frames greater than N over the data link from the first device to the second device in a single data transmission.
In a further illustrative embodiment of the invention, a device is provided for communicating data frames with another device over a data communication link. The device comprises a storage buffer capable of simultaneously storing no more than N data frames received over the data link from the other device, means for transmitting a request to the other device requesting that a number of data frames greater than N be transferred over the data communication link from the other device to the device, and means for receiving all of the number of requested data frames from the other device in a single data transmission.
REFERENCES:
patent: 5504861 (1996-04-01), Crockett et al.
patent: 5544347 (1996-08-01), Yanai et al.
patent: 5546549 (1996-08-01), Barrett et al.
patent: 5550976 (1996-08-01), Henderson et al.
patent: 5553302 (1996-09-01), Morrissey et al.
patent: 5615329 (1997-03-01), Kern et al.
patent: 5659756 (1997-08-01), Hefferon et al.
patent: 5680580 (1997-10-01), Beardsley et al.
patent: 5742792 (1998-04-01), Yanai et al.
patent: 5901327 (1999-05-01), Ofek
patent: 5912903 (1999-06-01), Nakayashiki et al.
patent: 5960216 (1999-09-01), Vishlitzky et al.
Alterescu Bruno
Castel Daniel
Shklarsky Gadi
Vishlitzky Natan
Yanai Moshe
EMC Corporation
Rinehart Mark H.
Thompson Marc D.
Wolf Greenfield & Sacks P.C.
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