Electrical computers and digital processing systems: memory – Storage accessing and control – Specific memory composition
Reexamination Certificate
1998-05-05
2001-03-13
Thai, Tuan V. (Department: 2752)
Electrical computers and digital processing systems: memory
Storage accessing and control
Specific memory composition
C711S100000, C711S147000, C711S161000
Reexamination Certificate
active
06202124
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to digital data storage systems. More particularly, the invention concerns a data storage system with an outboard data manager that performs data management operations without requiring substantial host involvement. Some exemplary data management operations include copy, migrate, move, recall, restore, defragment, reorganize, and the like.
2. Description of the Related Art
The manipulation, exchange, and storage of data are central functions in this information age. In a data storage system, there are many reasons to transfer data from one storage device to another. For example, many prudent computer users make duplicate or “backup” copies of their data to protect against data loss. Some other examples of data transfer operations are data reclamation, de-fragmentation, migration, etc. These generally involve some variation of copying data or moving data, where a data “move” entails a copy operation followed by the deletion of the source data from its original location.
To illustrate a common technique for data transfer,
FIG. 1
shows a typical data storage system
100
. The system
100
includes a host
102
coupled to a controller
104
and a controller
108
. The host
102
includes one or more processors that manage the controllers
104
,
108
.
The controllers
104
,
108
also include processing features, and serve to more specifically manage the operation of respective storage devices
106
,
110
. Namely, the controller
104
is coupled to the data storage unit
106
, which contains source data to be moved or copied. The controller
108
is coupled to a second data storage unit
110
, which is the destination for the data transfer operation. The storage devices
106
,
110
may comprise one or more magnetic hard drives, tape drives, libraries, or other digital data storage devices.
To copy data from the source
106
, the host
102
directs the controller
104
to copy source data from the device
106
and pass this data back to the host
102
. The host
102
forwards the data to the controller
108
, and directs the controller
108
to coordinate storage of the copied data at the target
110
. In the case of a data move, the source data is deleted after verifying that the copy operation has succeeded.
Although the foregoing backup technique is used widely, and some users may find this approach to be completely satisfactory, engineers at International Business Machines are continually seeking ways to improve data storage systems. One area of possible improvement concerns the processing burden experienced by the host
102
during data transfer operations. Particularly, the host
102
must serve as a conduit between the controllers
104
,
108
, which actually oversee the storage and retrieval of data from the devices
106
,
110
. This can involve a significant burden on the input/output (“I/O”) and processing capabilities of the host
102
, at the expense of application programs running on the host. In most cases, these application programs are the central functions of the system
100
, such as database management, mathematical modeling, financial analysis, network support, and other applications. Therefore, interruption of important processing tasks of the host
102
may be undesirable in many cases. Consequently, in some applications, known data copy and transfer systems are not completely adequate.
SUMMARY OF THE INVENTION
Broadly, the invention concerns a data storage system with an outboard data transfer module that directs data transfer operations without requiring substantial host involvement. This subsystem includes a host computer, one or more digital data storage devices, one or more device controllers interposed between the host computer and the storage devices, and a outboard data manager coupled to the host and the device controllers. In accordance with the invention, data transfer operations are initiated when the outboard data manager receives a data transfer request from the host. The request identifies source data residing on one or more source devices, the resulting format target data, and the target devices.
In response to this request, the outboard data manager retrieves a copy of the source data from the source device, formats retrieved data according to host information, and then transmits the copy to the target devices for storage therein. Thus, source data is copied from a source device to a target storage device via the outboard data manager without burdening the host by routing data through it. Some exemplary data transfer operations include copy, migrate, recall, restore, move, defragment, reorganize, and the like.
Accordingly, one embodiment of the invention relates to a method to perform data transfer operations in a data storage subsystem free from substantial host involvement. In another embodiment, the invention may be implemented to provide an apparatus, such as a data storage subsystem, including an outboard data manager, configured to perform data transfer operations free from substantial host involvement. In still another embodiment, the invention may be implemented to provide a signal-bearing medium tangibly embodying a program of machine-readable instructions executable by a digital data processing apparatus to perform method steps for performing data transfer operations in a data storage subsystem free from substantial host involvement.
The invention affords its users with a number of distinct advantages. First, the invention performs a data transfer operation without burdening the host with any substantial involvement. Consequently, the host is free to perform other tasks without delay, such as running application programs for users. Advantageously, data transfer operations performed by the invention are consistent and valid among the participating data storage devices, because the overall transfer operation is remotely overseen and verified by the host. For example, the host initiates each data transfer operation, protects the source data by serializing it, and prepares (or supervises preparation of) metadata related to the source data. The invention also provides a number of other advantages and benefits, which should be apparent from the following description of the invention.
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(Abstract) Tennison et al., IBM Technical Disclosure Bulletin, vol. 17, No. 9, pp. 2557-2558, Feb. 1975.
IBM Technical Disclosure Bulletin, Feb. 1983, pp. 4719-4721, Apr. 1993.
U.S. Patent Application No. 09/003,544, entitled “Host Storage Management Control of Outboard Data Movement”, filed Jan. 6, 1998 in the names of Robert Frederic Kern et al.
U.S. Patent Application No. 09/003,532, entitled “Host Storage Management Control of Outboard Data Movement Using Push-Pull Operations”, filed Jan. 6, 1998 in the names of Robert Frederic Kern et al.
Kern Robert Frederic
Kern Ronald Maynard
Micka William Frank
Sovik Mark Anthony
Dan Hubert & Assoc.
International Business Machines - Corporation
Thai Tuan V.
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