Patent EP0617362A1 successfully refreshed from Google Patents.
EP0617362A1
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EP
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Data back-up in data processing system
Assignee: International Business Machines Corp
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Filing: 1994-03-17
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Granted: —
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Expires: 2014-03-17
Abstract
Abstract A method and means for asynchronous remote data duplexing at a distant location from copies based at a primary site storage subsystem, which copying is non-disruptive to executing applications, and further in which any data loss occasioned by losses in flight or updates never received at the time of any interruption between the primary and remote sites are accounted for at the remote site. The method assigns a token and unique sequence number responsive to each write operation at the primary site, and sends the tokens + numbers and data updates to the remote site. The method relies upon the sequence number to establish a sequence and define gaps therein to ascertain missing updates.
Inventors
- 👤 Robert Wesley Shomler
- 👤 James E. Mcilvain
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 12:34
CPC Classifications
G; G06; G06F; G06F11/00; G06F11/07; G06F11/16; G06F11/20; G06F11/2053; G06F11/2056; G06F11/2082; G06F11/2064; G11; G11C; G11C29/00; G11C29/70; G11C29/74
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
132 words
A method for updating back-up data stored at a secondary storage site in response to write update operations to external storage at a primary site, the method comprising the steps of: responsive to a write update operation at the primary site, generating a write token for said operation including a unique sequence number and an external storage address; sending messages from the primary to the secondary site, each message selectively including a list of recently generated write tokens plus update data corresponding to listed tokens sent in the same message or in previous messages; maintaining at the secondary site a pending write queue and responsive to each received message from the primary site, matching update data with tokens; and scheduling and writing matched updates at the secondary site in sequence number order.
Claim 2
Dependent Claim
74 words
A method as claimed in claim 1, wherein said method further comprises the steps of: responsive to the interruption of at least some portion of the sequence of updates, scanning the maintained pending write queue at the secondary site and interpreting the sequenced tokens and updates received at the site so as to present a consistent-in-time image of data manifest by the sequence of write update operations as it was at the primary site.
Claim 3
Dependent Claim
66 words
A method as claimed in to claim 1 or claim 2, wherein the step of sending messages further includes the steps of: sending messages between the source and a plurality of remote sites including either sending at least one message to a first site, sending at least another message to a second site, or sending at least one message to both said first and second sites.
Claim 4
Dependent Claim
201 words
A data processing system comprising a processor, an operating system (OS) resident at said processor, an external store, means responsive to applications executing on said processor for writing updates to external storage through calls to said OS, and means for propagating dual copies of said updates to a site remote from said external storage and asynchronous to application execution, said propagating means including means for asynchronously writing said dual copies of said updates at said remote site, wherein said dual copy means comprises: means responsive to a write update operation at the external store for forming a write token including a unique update sequence number and an external store address; means for sending messages over a communications path between the external store and the remote site, each message selectively including a list of recently generated write tokens and write tokens and counterpart update data of listed tokens sent in the same message or in previous messages; and means at the remote site responsive to each received message for maintaining a pending write queue to match data with tokens, for scheduling and writing the update data at the remote site only when matched with the counterpart token and in sequence number order.
References Cited (Backward Citations)
WO1991020034A1
Cited
US5155845A
Cited
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