Electrical computers and digital processing systems: multicomput – Remote data accessing
Reexamination Certificate
1998-10-30
2001-09-11
Barot, Bharat (Department: 2154)
Electrical computers and digital processing systems: multicomput
Remote data accessing
C709S202000, C709S219000, C709S225000, C709S229000, C707S793000, C707S793000
Reexamination Certificate
active
06289375
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to digital data processing, and more particularly to the management of networks of digital data storage devices.
BACKGROUND OF THE INVENTION
Modern computer systems have driven a demand for enormous amounts of data storage. Data traditionally has been stored in one or more mass data storage devices, such as rotating magnetic disk drives or tape drives, attached to a single computer system. As computer systems have become larger, faster, and more reliable, there has been a corresponding increase in need for storage capacity, speed and reliability of the storage devices. Increases in the data storage capacity and reliability of storage devices have been dramatic in recent years. But with all the improvements to the devices themselves, there are certain limitations to what can be accomplished. Additional configurations of storage devices have increasingly been offered in recent years to meet demand for larger capacity, faster, more reliable, and more accessible data storage.
One example of alternative configurations is the rapidly increasing popularity of so-called “RAIDs”, i.e., redundant arrays of independent disks. A RAID stores data on multiple storage devices in a redundant fashion, such that data can be recovered in the event of failure of any one of the storage devices in the redundant array. RAIDs are usually constructed with rotating magnetic hard disk drive storage devices, but may be constructed with other types of storage devices, such as optical disk drives, magnetic tape drives, floppy disk drives, etc. Various types of RAIDs providing different forms of redundancy are described in a paper entitled “A Case for Redundant Arrays of Inexpensive Disks (RAID)”, by Patterson, Gibson and Katz, presented at the ACM SIGMOD Conference, June, 1988. Patterson, et al., classify five types of RAIDs designated levels
1
through
5
. The Patterson nomenclature has become standard in the industry.
Another example of a storage alternative is the concept of a storage subsysteim A storage subsystem implies a greater degree of independence from a host computer system than is typically found in an isolated storage device. For example, the subsystem may be packaged in a separate cabinet, with its own power supply, control software, diagnostics, etc. The subsystem may have a single storage device, but more typically contains multiple storage devices. The notion of a storage subsystem and a RAID are not necessarily mutually exchlsive; in fact many RAIDs are constructed as semi-independent storage subsystems, which communicate with a host through a communication link having a defined protocol. It is possible in such subsystems that the host is not even aware of the existence of multiple data storage units or data redundancy in the storage subsystem. To the host, the subsystem may appear to be a single very large storage device.
A configuration of multiple storage devices need not be attached to only a single host computer system. It might be that multiple computer systems are configured to share multiple storage devices. Thus, configurations of storage devices can be generalized to the concept of a storage network.
As used herein, a storage network is a configuration of multiple data storage devices, connected to one or more host computer systems, such that there is a communication path from each storage device to each host system which does not cross the system bus of another host system Because there exists a direct communication path from each system to each storage device, data on any device is readily accessible to any of the systems. Storage devices in a storage network are not necessarily identified with or controlled by a host This latter feature distinguishes a storage network from a simple network of computer systems, each having its own local storage devices. Thus, in certain computing environments, a storage network facilitates sharing of data and improved performance over a conventional network of host systems.
While it is theoretically possible to construct and maintain complex storage networks shared among multiple host computer systems using prior art hardware, in reality this is an error-prone and difficult task. Documentation and software support may be primitive or non-existent. A user must determine how to operate, configure and attach devices, and may have to write his own custom software routines to provide proper support for the network. Optimum physical configurations may depend on logical configurations and modes of operation, such as one or more RAID levels. There may be numerous hardware dependencies and limitations, such as number and type of devices that may communicate with a single I/O controller or adapter. Data may have to be collected from multiple sources and analyzed to provide needed information. All these requirements place substantial demands on the time, expertise and other resources of the user.
It would be desirable to support the construction and maintenance of storage networks with software which assists the user.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide enhanced data processing capability.
Another object of this invention is to provide enhanced support for calls to a server from an information processing network.
Another object of this invention is to provide enhanced support for distributed programs.
Another object of this invention is to enhance the capability to monitor devices using a distributed monitoring program.
Another object of this invention is to provide enhanced support for storage networks attached to multiple host computer systems.
An agent receives requests over an information processing network. Each request contains a plurality of parameters. The process of responding to the request varies depending on the values of the parameters. The agent includes a plurality of functions used to respond, each function being used for one or more sets of parameter values. Upon receipt of a request, the agent constructs a hash key using the parameter values, and uses the hash key to index an entry in a hash function table. The hash function table contains a plurality of entries, each entry having a set of parameter values and a pointer corresponding to the function used to service an information request for the indicated parameter values. Upon locating the appropriate entry, the pointer is used to call the function to service the request.
Preferably, requests may include wild card parameters. The agent refers to a wild card table to expand a wild card parameter into multiple parameter values which the wild card may assume. These parameter values are then used to construct a set of expanded requests, each request of the set corresponding to one of the parameter values. The set of expanded requests are then used to generate a corresponding set of hash keys, and the appropriate function is called for each respective expanded request.
In the preferred embodiment, the agent (also called a local agent) is part of a larger distributed storage management program which supports management of storage networks connected to multiple host computer systems through one or more controllers in each respective host. The distributed storage management program comprises a central manager portion and a separate agent in each of the host computer systems. The agents gather data and communicate with the manager across the information processing network, which is a communications path independent of the storage network. The manager collates the data from different agents to produce a coherent view of the network.
In accordance with the preferred embodiment, requests are generally for information concerning storage networks attached to a local host computer system. Each local agent independently collects data from the storage network(s) attached to the respective host in which the agent is located. Thus the view of the network obtained by any particular local agent is the view of its host. The agent operates as a server, responding to data requests from the cen
Knight Greg
Nicholson Robert Bruce
Barot Bharat
International Business Machines - Corporation
Truelson Roy W.
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