EP0674263A1
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EP
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Asynchronous remote data copying
Assignee: International Business Machines Corp
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Filing: 1995-03-02
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Granted: —
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Expires: 2015-03-02
Abstract
Abstract Asynchronous remote data duplexing at a distant location is performed from copies based at a primary site storage subsystem using first and second pluralities of subsystems 12, 14 at primary and remote sites respectively. Each of the first plurality of subsystems is independently coupled to one or more of the second plurality of subsystems. The first plurality of subsystems are interconnected and the second plurality of subsystems are also interconnected. The method utilizes checkpoint messages to maintain sequence integrity between the first and second plurality of subsystems without the use of a centralized communications service.
Inventors
- 👤 William Frank Micka
- 👤 Robert Wesley Shomler
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 21:20
CPC Classifications
G; G06; G06F; G06F11/00; G06F11/07; G06F11/16; G06F11/20; G06F11/2053; G06F11/2056; G06F11/2071; G06F11/2074; G06F11/2064; G11; G11C; G11C29/00; G11C29/70; G11C29/74; Y; Y10; Y10S; Y10S707/00; Y10S707/99931
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
139 words
A method of operating an asynchronous remote data copy system (20) including a primary site having a first plurality of subsystems (12) interconnected by a first coupling means (16), and a secondary site remote from the primary site having a second plurality of subsystems (14) interconnected by a second coupling means, each of the second plurality of subsystems being independently coupled to a counterpart one of the first plurality of subsystems, said method comprising the steps of: in the first plurality of subsystems; sending a checkpoint signal to each of the first plurality of subsystems; sending updated data and the checkpoint signal to each of the counterpart coupled second plurality of subsystems; and in the second plurality of subsystems; receiving the updated data and checkpoint signals; and coordinating the writing of the updated data based upon the checkpoint signals.
Claim 2
Dependent Claim
29 words
The method of claim 1, further comprising the step of distributing a sequence signal at the primary site, said checkpoint signal having a predetermined relationship with the sequence signal.
Claim 3
Dependent Claim
96 words
The method of claim 1 or 2 further comprising the steps of: activating each of the first plurality of subsystems to communicate with the other subsystems in said first plurality of subsystems; activating each of the first plurality of subsystems to communicate with its counterpart coupled subsystem in the second plurality of subsystems; building at least one configuration table in each of the first plurality of subsystems such that each of the first plurality of subsystems can identify all of the other subsystems in said first plurality of subsystems; and synchronizing the first plurality of subsystems.
Claim 4
Independent Claim
79 words
The method of any preceding claim in which the coordinating step further comprises the steps of: receiving copy active messages in the second plurality of subsystems; building copy active tables in the second plurality of subsystems; synchronizing copy operations of the second plurality of subsystems; receiving the checkpoint messages in the second plurality of subsystems; performing a rendezvous for all checkpoint messages in the second plurality of subsystems; and applying the updated data at the second plurality of subsystems.
Claim 5
Independent Claim
80 words
The method of any preceding claim, further comprising the steps of: causing each of said first plurality of subsystems to asynchronously generate a sequence of updates; ordering each of said sequences in accordance with the received sequence signal and checkpoint signal; asynchronously communicating sequences of updates from each of the first plurality of subsystems into a buffered portion of a counterpart subsystem; and applying the buffered sequences at the second plurality of subsystems as a function of each checkpoint message.
Claim 6
Independent Claim
300 words
A method of operating an asynchronous remote data copy system (20) including a primary site having a first plurality of subsystems (12) interconnected by a first coupling means (16), and a secondary site remote from the primary site having a second plurality of subsystems (14) interconnected by a second coupling means, each of the second plurality of subsystems being independently coupled to a counterpart one of the first plurality of subsystems, said method comprising the steps of: (a) at the primary site responsive to initiation of a start copy operation, ascertaining at each subsystem the subset of the plurality of DASD subsystems forming the copyset group, designating one of the plurality of subsystems as a clocking and checkpoint message source, each checkpoint message including a sequence clock value and an increased sequence number; (b) at the secondary site, repeating step (a) for counterpart ones of the DASD subsystems; (c) at the primary site, periodically generating clocking signals and checkpoint messages by said designated subsystem and broadcasting said signals and messages as they occur to other subsystems forming the copyset group including itself, at each subsystem in the copyset group, and (1) asynchronously forming a local sequence of updated records, (2) embedding said signals and messages into the sequence to form a time discriminated total ordering of updated records, and (3) remitting at least a portion of the sequence to a buffer portion of the counterpart DASD subsystem at the secondary site; and (d) at the secondary site, applying a checkpoint message to the designated subsystem operative as a synchronizing source by each subsystem in the copyset group and writing the sequences or portions thereof stored in the buffered portions of said subsystems to DASD only upon a signal from said designated subsystem indicative of its receipt of all send messages.
Claim 7
Dependent Claim
41 words
The method according to claim 6, wherein each checkpoint message signifies that all DASD records with a clock signal with a sequence number that is less than the checkpoint message sequence clock value have been transmitted to the counterpart secondary subsystem.
Claim 8
Dependent Claim
138 words
An asynchronous remote data copy system (20) including a primary site having a first plurality of subsystems (12) interconnected by a first coupling means (16), and a secondary site remote from the primary site having a second plurality of subsystems (14) interconnected by a second coupling means, each of the second plurality of subsystems being independently coupled to a counterpart one of the first plurality of subsystems, the first plurality of subsystems including means for sending a checkpoint signal to each of the first plurality of subsystems; and means for sending updated data and the checkpoint signal to each of the counterpart coupled second plurality of subsystems; and the second plurality of subsystems including means for receiving the updated data and checkpoint signals; and means for coordinating the writing of the updated data based upon the checkpoint signals.
Claim 9
Dependent Claim
29 words
The system of claim 8, further comprising the means for distributing a sequence signal at the primary site, said checkpoint signal having a predetermined relationship with the sequence signal.
Claim 10
Dependent Claim
58 words
The system of claim 9 or 10 in which the checkpoint signal sending means comprises: means for sending a checkpoint message to the first plurality of subsystems; and means responsive to the checkpoint message sending means for inserting the checkpoint message into an update data sequence from each of said first plurality of subsystems to its counterpart subsystem.
References Cited (Backward Citations)
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