US 5,210,865 A · Transferring data between storage media while maintaining host processor access for I/O operations

Abstract

A system and method for transferring data from a first storage medium to a second storage medium, each of the storage media being divided into corresponding data blocks, the method comprising steps of: (a) reading data stored in a first data block in the first storage medium, the first data block initially constituting a current data block; (b) comparing data read in the current data block to data stored in a corresponding data block in the second storage medium; (c) if the data compared in step b are identical, reading data stored in a different data block in the first storage medium, the different data block becoming the current data block, and returning to step b; (d) modifying the data stored in one of the storage media such that the data in the current data block is identical to the corresponding data in the second storage medium; and (e) rereading the data in the current data block and returning to step b.

Claims23

Dependent claims

A method of transferring data between a first storage medium and a second storage medium, at least said first storage medium being accessible to one or more host processors for I/O operations that include writing data to said first storage medium, each of said storage media including data blocks with at least some data blocks of said first storage medium having corresponding data blocks in said second storage medium, said method comprising the steps of:

(a) reading data stored in a first data block in said first storage medium, the first data block initially constituting a current data block;
(b) comparing the data read in said current data block to data stored in a corresponding data block in said second storage medium;
(c) if the data compared in step b are identical, reading data stored in another data block in said first storage medium, said another data block becoming the current data block, and returning to step b;
(d) if the data compared in step b are not identical, modifying the data stored in one of said storage media by transferring data between said storage media to cause the data in said current data block and the data in said corresponding data block in said second storage medium to be identical while maintaining access to said first storage medium for said I/O operations by said one or more of said host processors;
and
(e) rereading the data in said current data block and returning to step b.

3 more elements

A method of managing a shadow set of storage media that are accessible by one or more host processors for I/O operations that include writing data thereto, each one of said storage media having storage locations at least some of which correspond to storage locations of another one of said storage media, the method comprising the steps of:

A. carrying out successive comparisons of data stored in said corresponding locations of said plurality of said storage media, respectively;
and
B. performing a management operation on at least one of said storage media, said management operation comprising, for each of said corresponding locations where said comparisons indicated that the data in said corresponding locations were not identical;
a. reading data from locations in a first one of said storage media and writing said data to said corresponding locations a second one of said storage media while maintaining access to at least said first storage medium for said I/O operations by said one or more of said host processors;
b. comparing the data in said corresponding locations after said writing to determine if the data in said corresponding locations are identical;
and
c. repeating step a if the comparison of step b indicates that the data in said corresponding locations are not identical, otherwise terminating said management operation as to said storage locations.

4 more elements

An apparatus for managing a shadow set of storage media accessible by one or more host processors for I/O operations that include writing data thereto, each one of said storage media having storage locations at least some of which correspond to storage locations of another one of said storage media, comprising:

means for carrying out successive comparisons of data stored in said corresponding locations of said plurality of said storage media, respectively;
and
means, responsive to said comparisons, for performing a management operation on at least one of said storage media, said management operation comprising, for each of said corresponding locations where said comparisons indicated that the data in said corresponding locations were not identical;
a. reading data from locations in a first one of said storage media and writing said data to said corresponding locations in a second one of said storage media while maintaining access to at least said first storage medium for said I/O operations by said one or more of said host processors;
b. comparing the data in said corresponding locations after said writing to determine if the data in said corresponding locations are identical;
and
c. repeating step a if the comparison of step b indicates that the data in said corresponding locations are not identical, otherwise terminating said management operation as to said storage locations.

4 more elements

Dependencies are inferred from the claim text.

Transferring data between storage media while maintaining host processor access for I/O operations

Life of this patent

Transferring data between storage media while maintaining host processor access for I/O operations

Life of this patent

Abstract

Claims23