US 5,680,640 A · System for migrating data by selecting a first or second transfer means based on the status of a data element map initialized to a predetermined state

Abstract

A system and method for providing on-line, real-time, transparent data migration from a first data storage system to a second data storage system. The first data storage system which had previously been coupled to a host, network or other data processing system is disconnected from the host and connected to a second data storage system. The second data storage system is coupled to the host or data processing system. The second data processing system includes a data map or table which indicates which data elements are stored on the second data storage system and which corresponding data elements on the first data processing device have been copied to the second data storage system. When the host, network or data processing system requests data from a data storage system, the second data storage system determines whether or not the data is stored on the second or first data storage system. If the data is stored on the second data storage system, the data is made available to the requesting device. If the data is not stored on a second data storage system, the second data storage system issues a request to the first data storage system, retrieves the data, makes the data available to the requesting device, writes the data to the second data storage system and updates the data element map or table. When not busy servicing other requests, the second data storage system scans the data map or table to determine which data elements from the first data storage device have not been copied to the second data storage device, and performs copying of the data and updating of the data map or table in the background, independent of any coupled host, network or other similar data processing device.

Claims26

Dependent claims

A replacement storage device for supplanting a first data storage device in a data processing system including a host computer for processing data, interface means on each of the host computer means and the first data storage device, and a link connecting the interface means, the host computer means issuing requests to transfer data to and from the first data storage device over the link, said replacement data storage device comprising:

A) a data store;
B) first connection means for connection to the interface means on the host computer means in lieu of link,
C) second connection means for connection to the interface means of the first data storage in lieu of the link,
D) first transfer means connected to said first connection means and said data store for receiving transfer requests from the host computer,
E) second transfer means connected to said connection means for effecting a migration of data from addressed locations in the first data storage device to corresponding locations in said data store,
F) data maps means initialized to a predetermined state prior to the data migration for maintaining the status of the data migration, and
G) control means responsive to said data map means for normally selecting said second transfer means for migrating data from the first data storage device to said data store in said replacement data storage device, said control means responding to a data transfer request to said first transfer means by enabling said second transfer means to effect a transfer of the data identified by the data transfer request between said data store and the host computer, said second transfer means updating said data map means for each transfer produced thereby.

4 more elements

In a computer system comprising a first data storage device holding a plurality of data elements and a data processing device for reading data from and writing data to the first data storage device, a second data storage device coupled to the first data storage device, said second data storage device being adapted for providing an on-line transparent data migration of data elements thereto from the first data storage device, said second data storage device comprising:

A ) a data store,
B) first connection means for connection to the data processing device,
C) second connection means for connection to the first data storage device,
D) transfer means connected to said first and second connection means and said data store for receiving transfer requests from the data processing device,
E) control means for enabling said transfer means to migrate data from the first storage device to said data store, said control means including a data element map for indicating whether a data element is stored on said second data storage device, and means responsive to at least said indication of whether said at least one predetermined data element is stored in said second data storage device for obtaining data from the first data storage device and for storing said obtained data on said second data storage device.

2 more elements

In a system including a data processing device connected to a first storage device for normally transferring data therebetween and a second storage device for supplanting the first storage device for at least a portion of the data stored thereon, a method for migrating the data from the first storage device to the second storage device comprising the steps of:

A. interposing the second storage device between the data processing system and the first storage device,
B. incorporating a transfer process for reading data from the first data storage device to the second data storage device,
C. establishing a data element map that is initialized to a predetermined state for identifying data that has migrated to the second storage device, and
D. controlling the transfer process in response to the contents of the data element map by selecting a first transfer process mode transferring requested data in response to a transfer request from the data processing system and by selecting a second transfer process mode causing a transfer of data from sequential locations in the first data storage device when the first transfer process mode is inactive, each of the transfer process modes migrating data to the second data storage device and updating the data element map.

1 more element

A method for migrating data from a first data storage device previously coupled to a data processing device to a second data storage device presently coupled to the data processing device and to the first data storage device, the first data storage device including a plurality of data elements previously accessed by the data processing device, at least some of the plurality of data elements to be migrated to the second data storage device, the second data storage device including a data element map including at least an indication of whether a data element having a predetermined data element storage location address is stored on the second data storage device, said method comprising the steps of:

configuring said second data storage device to include a plurality of data element storage location addresses corresponding to data element storage location addresses on the first data storage device;
receiving at the second data storage device from the data processing device, at least one of a data element read and a data element write request for initiating the transfer of at least one data element;
searching the data element map to determine if said at least one data element is stored on the second data storage device;
and
selectively copying the at least one data element from the first to the second data storage device in response to said searching.

2 more elements

Dependencies are inferred from the claim text.

System for migrating data by selecting a first or second transfer means based on the status of a data element map initialized to a predetermined state

Life of this patent

System for migrating data by selecting a first or second transfer means based on the status of a data element map initialized to a predetermined state

Life of this patent

Abstract

Claims26