US5577222A
Expired / Lapsed
US
⏱️ 0.0 years remaining
System for asynchronously duplexing remote data by sending DASD data grouped as a unit periodically established by checkpoint based upon the latest time value
Assignee: International Business Machines Corp
•
Filing: 1992-12-17
•
Granted: 1996-11-19
•
Expires: 2012-12-17
Abstract
Abstract A system for asynchronously duplexing direct access storage device (DASD) data in a plurality of DASD subsystems has the advantage of decoupling the data duplexing operation from the DASD write I/O operation. This ensures the write does not incur unnecessary wait states in the subsystem. By establishing a sequence checkpoint at which time a set of information packets are grouped together and processed as a single sequence unit, this decoupling and independent operation takes place. Through this independence, data copying to a secondary location can take place without affecting the performance of the subsystems and also not affecting the corresponding integrity of the data that is being updated.
Inventors
- 👤 William F. Micka
- 👤 Claus W. Mikkelsen
- 👤 Robert W. Shomler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 10:27
CPC Classifications
G; G06; G06F; G06F11/00; G06F11/07; G06F11/16; G06F11/20; G06F11/2053; G06F11/2056; G06F11/2071; G06F11/2074; G06F11/2064; Y; Y10; Y10S; Y10S707/00; Y10S707/99931
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
174 words
In a system for duplexing remote data, the system including a plurality of direct access storage device (DASD) subsystems, each subsystem including a plurality of information packet messages associated with DASD data write operation, each of the information packet messages having a time value associated therewith, each of the information packet messages having a sequence number, a method for asynchronously duplexing DASD data content from the DASD subsystems comprising the steps of: (a) establishing a session with each of the plurality of subsystems; (b) reading the information packet messages from each of the DASD subsystems after a write operation to the subsystem; (c) establishing a periodic sequence checkpoint based on a latest time value associated with one of the plurality of information packet messages to group a plurality of information packet messages together as a single sequence unit; (d) sending the sequence unit to a secondary location for processing; (e) obtaining DASD data associated with the information packet messages from each of the subsystems; and (f) sending the DASD data to a secondary location.
Claim 2
Dependent Claim
174 words
In a system for duplexing remote data, the system including a plurality of direct access storage device (DASD) subsystems, each subsystem including a plurality of information packet messages associated with DASD data write operation, each of the information packet messages having a time value associated therewith, each of the information packet messages having a sequence number, a method for asynchronously duplexing DASD data content from the DASD subsystems comprising the steps of: (a) establishing a session with each of the plurality of subsystems; (b) reading the information packet messages from each of the DASD subsystems after a write operation to the subsystem; (c) establishing a periodic sequence checkpoint based on a latest time value associated with one of the plurality of information packet messages to group a plurality of information packet messages together as a single sequence unit; (d) sending the sequence unit to a secondary location for processing; (e) obtaining DASD data associated with the information packet messages from each of the subsystems; and (f) sending the DASD data to a secondary location.
Claim 3
Dependent Claim
41 words
The method of claim 1 in which step (b) further comprises the steps of: (a) setting a time of day clock value for each subsystem that can be correlated with a clock time for the other of the plurality of subsystems.
Claim 4
Dependent Claim
25 words
The method of claim 2 in which: each of the subsystems create and queue an information packet message each time a write operation is processed.
Claim 5
Dependent Claim
81 words
The method of claim 1 in which step (c) further comprises the steps of: (a) searching for a latest time value of the information packet messages from each of the plurality of subsystems; (b) establishing the earliest of the latest time value for the information packet messages as a checkpoint; and (c) grouping all information packet messages from the plurality of subsystems which have a time value that is earlier than the time value of the checkpoint into a sequence unit.
Claim 6
Dependent Claim
39 words
The method of claim 4 which further comprises the steps of: (a) querying a subsystem if there is no write operation received from the subsystem; and (b) causing the subsystem to send the last sent information packet time value.
Claim 7
Dependent Claim
38 words
The method of claim 4 which further comprises the steps of: (a) querying a subsystem if there is no write operation received from the subsystem; and (b) causing the subsystem to send at least one information packet message.
Claim 8
Dependent Claim
165 words
In a system for duplexing remote data, the system including a plurality of direct access storage device (DASD) subsystems, each subsystem including a plurality of information packets associated with a DASD data write operation, each of the information packets having a time value associated therewith, each of the information packets having a sequence number, a global sequencer for asynchronously duplexing information packet messages from the DASD subsystems comprising; means for establishing a session with each of the plurality of subsystems; means responsive to the session establishing means for reading the information packets from each of the DASD subsystems after a write operation to the subsystems; means responsive to the reading means for establishing a periodic sequence checkpoint based on a latest time value associated with one of the plurality of information packets to group a plurality of information packets together as a single sequence unit; and means responsive to sequence checkpoint establishing means for sending the single sequence unit to a secondary location for processing.
Claim 9
Dependent Claim
165 words
In a system for duplexing remote data, the system including a plurality of direct access storage device (DASD) subsystems, each subsystem including a plurality of information packets associated with a DASD data write operation, each of the information packets having a time value associated therewith, each of the information packets having a sequence number, a global sequencer for asynchronously duplexing information packet messages from the DASD subsystems comprising; means for establishing a session with each of the plurality of subsystems; means responsive to the session establishing means for reading the information packets from each of the DASD subsystems after a write operation to the subsystems; means responsive to the reading means for establishing a periodic sequence checkpoint based on a latest time value associated with one of the plurality of information packets to group a plurality of information packets together as a single sequence unit; and means responsive to sequence checkpoint establishing means for sending the single sequence unit to a secondary location for processing.
Claim 10
Dependent Claim
41 words
The sequencer of claim 7 in which the session establishing means comprises: means for setting a time of day clock value for each subsystem that can be correlated with a clock time for the others of the plurality of the subsystems.
Claim 11
Dependent Claim
25 words
The sequencer of claim 8 in which each of the subsystems create and queue an information packet message each time a write operation is processed.
Claim 12
Dependent Claim
91 words
The sequencer of claim 7 in which the sequence checkpoint establishing means comprises: means for searching for a latest time value of the information packet messages from each of the plurality of subsystems; means responsive to the searching means for establishing the earliest of the latest time value information packets as a checkpoint; and means responsive to the time value establishing means for grouping all information packets from the plurality of subsystems which have a time value that is earlier than the time value of the checkpoint into a sequence unit.
Claim 13
Dependent Claim
43 words
The sequencer of claim 10 which further comprises: means for querying a subsystem if there is no write operation received from the subsystem; and means responsive to the querying means for causing the subsystem to send the last sent information packet time value.
Claim 14
Dependent Claim
42 words
The sequencer of claim 9 which further comprises: means for querying a subsystem if there is no write operation received from the subsystem; and means responsive to the querying means for causing the subsystem to send at least one information packet message.
Claim 15
Dependent Claim
164 words
A computer readable medium containing program instructions for asynchronously duplexing direct access storage device (DASD) data content from DASD subsystems in a system including a plurality of subsystems, each subsystem including a plurality of information packet messages associated with DASD data write operations, each of the information packet messages having a time value associated therewith, each of the information packet messages having a sequence number, the program instructions comprising: establishing a session with each of the plurality of subsystems; reading the information packet messages from each of the DASD subsystems after a write operation to the subsystem; establishing a sequence checkpoint based on a latest time value associated with one of the plurality of information packet messages to group a plurality of information packet messages together as a single sequence unit; sending the sequence unit to a secondary location for processing; obtaining DASD data associated with the information packet messages from each of the subsystems; and sending the DASD data to a secondary location.
Claim 16
Dependent Claim
164 words
A computer readable medium containing program instructions for asynchronously duplexing direct access storage device (DASD) data content from DASD subsystems in a system including a plurality of subsystems, each subsystem including a plurality of information packet messages associated with DASD data write operations, each of the information packet messages having a time value associated therewith, each of the information packet messages having a sequence number, the program instructions comprising: establishing a session with each of the plurality of subsystems; reading the information packet messages from each of the DASD subsystems after a write operation to the subsystem; establishing a sequence checkpoint based on a latest time value associated with one of the plurality of information packet messages to group a plurality of information packet messages together as a single sequence unit; sending the sequence unit to a secondary location for processing; obtaining DASD data associated with the information packet messages from each of the subsystems; and sending the DASD data to a secondary location.
References Cited (Backward Citations)
US4020466A
Cited
US4159517A
Cited
US4507751A
Cited
US4503499A
Cited
US4916605A
Cited
US4814971A
Cited
US5148540A
Cited
US5321832A
Cited
US5170480A
Cited
US5155845A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-11-19 | 2000-05-20 | 2000-11-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-11-19 | 2004-05-20 | 2004-11-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-11-19 | 2008-05-20 | 2008-11-19 | $7700.00 | Window Closed / Lapsed |