Electrical computers and digital processing systems: multicomput – Computer network managing
Reexamination Certificate
1998-10-30
2001-06-26
Luu, Le Hien (Department: 2152)
Electrical computers and digital processing systems: multicomput
Computer network managing
C710S008000, C710S015000
Reexamination Certificate
active
06253240
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 subsystem. 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 exclusive; 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 PO 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 storage capability.
Another object of this invention is to provide enhanced support for data storage networks.
Another object of this invention is to enhance the capability to manage a network of data storage devices attached to multiple computer systems.
Another object of this invention is to reduce the costs of constructing and maintaining a network of data storage devices attached to multiple computer systems.
A storage network comprising multiple data storage devices attached to multiple host computer systems is supported by a distributed storage management program. The distributed storage management program includes a separate agent in each of the host computer systems, and a manager which may be in one of the host computer systems or in a separate computer system not directly coupled to the storage network. The agents gather data and communicate with the manager across a communications path which is 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, 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 central manager. The local agent is not a mere passive entity responding only to data requests, but actively builds an internal topological view of the network as seen by its host and collects data such as error events. This view is stored in a complex series of data structures which permit rapid access to individual device data, as well as to topological data, for use in responding to a variety of information requests from the central manager. The local agent contains intelligent resolution routines for resolving certain unknown devices in its topological view of the networks attached to its host.
In the preferred embodiment, it is possible that despite the intelligent resolution routines employed by the local agent, no particular host will have a complete view of the network. I.e., each host will be unaware of some devices contained in other hosts, or the other hosts themselves. The manager produces the complete network view from the collection and resolution of data from all local agents.
In the preferred embodiment, the storage network is a network of storage devices and host adapter devices connected by a communications medium employing the IBM Serial Storage Architecture (SSA) communications protocol. This protocol is designed to efficiently support transmission of data between multiple hosts and storage devices in a storage network, but does not easily support communication of data at a higher programming level. Specifically, it does not readily support typical client-server communication, such as remote p
Axberg Gary Thomas
Baldwin Duane Mark
Heitman Allen Robert
Immaneni Uma Devi
Knight Greg
International Business Machines - Corporation
Luu Le Hien
Truelson Roy W.
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