EP0098928A2
Expired / Lapsed
EP
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Method and apparatus for logging journal data using a log write ahead data set
Assignee: International Business Machines Corp
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Filing: 1983-05-02
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Granted: —
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Expires: 2003-05-02
Abstract
Abstract The invention provides a computing apparatus and method for maintaining a journal log 80. The computing apparatus includes volatile storage for storing a log buffer 60 and a non-volatile storage for storing a journal log 80. Non-volatile storage means 70 are provided for storing in a write-ahead data set a plurality of short data blocks. The log buffer contents are written to the write-ahead data set responsive to a process epoch occurring before the log buffer is filled. The log buffer contents are written to the journal log upon the log buffer being filled. The redoing or undoing of data base changes is made with reference to the write ahead data set only in the case of a system failure resulting in loss of log buffer data not yet written to the journal log; otherwise data base changes are redone or undone with reference to the log buffer or journal log.
Inventors
- 👤 Dieter Gawlick
- 👤 James Nicholas Gray
- 👤 Wallace Mitsuo Iimura
- 👤 Ronald Lester Obermarck
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 18:40
CPC Classifications
G; G06; G06F; G06F9/00; G06F9/06; G06F9/46; G06F9/461; G06F9/463; G06F11/00; G06F11/07; G06F11/14; G06F11/1471; G06F16/00; G06F9/44; Y; Y10; Y10S; Y10S707/00; Y10S707/99951; Y10S707/99952; Y10S707/99953
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
168 words
A method for operating a computing apparatus having a central processor, one or more non-volatile storage devices and a volatile main storage including a log buffer, to log the creation, deletion and modification of recoverable objects, the improvement comprising the steps of: preformatting a write ahead data set on a temporary non-volatile storage (70) to store a plurality of short data blocks; writing log records to a log buffer (60) in main storage; responsive to a process epoch occurring before the log buffer is filled, forcing log buffer contents to the write ahead data set; writing the log buffer contents to a journal log in a permanent non-volatile storage (80) upon the log buffer being filled;and redoing or undoing data base changes with reference to the write ahead data set only in the case of a system failure resulting in loss of log buffer data not yet written to the journal log, otherwise redoing or undoing data base changes with reference to the log buffer or journal log.
Claim 2
Independent Claim
168 words
A method for operating a computing apparatus having a central processor, one or more non-volatile storage devices and a volatile main storage including a log buffer, to log the creation, deletion and modification of recoverable objects, the improvement comprising the steps of: preformatting a write ahead data set on a temporary non-volatile storage (70) to store a plurality of short data blocks; writing log records to a log buffer (60) in main storage; responsive to a process epoch occurring before the log buffer is filled, forcing log buffer contents to the write ahead data set; writing the log buffer contents to a journal log in a permanent non-volatile storage (80) upon the log buffer being filled;and redoing or undoing data base changes with reference to the write ahead data set only in the case of a system failure resulting in loss of log buffer data not yet written to the journal log, otherwise redoing or undoing data base changes with reference to the log buffer or journal log.
Claim 3
Dependent Claim
40 words
The method of claim 1, comprising the further step of: restoring the main storage buffer during system restart by copying into said buffer short blocks from the temporary non-volatile storage containing records not yet written to the permanent non-volatile storage.
Claim 4
Independent Claim
91 words
The method of claims 1 and 2 for operating a computing apparatus for storing a plurality of sequential records selectively in a buffer and non-volatile storage, the non-volatile storage including a first store and a second store, characterized by the steps of: writing buffer contents to said first store in response to said buffer being filled;and writing selected buffer contents in short blocks to said second store in response to a request received before the buffer is filled to write to non-volatile storage the buffer contents through a specified sequential record.
Claim 5
Dependent Claim
39 words
The method of claim 3, further characterized by the step: responsive to a failure resulting in loss in said buffer of data not yet written to said first store, restoring said buffer from data written to said second store.
Claim 6
Dependent Claim
49 words
The method of claim 3, further characterized by the steps: segmenting said buffer into a plurality of segments, each segment equal in length to a short block;and responsive to said request received before the buffer is filled, writing to said second store only buffer segments not previously written thereto.
Claim 7
Dependent Claim
207 words
A computing apparatus for logging records of the creation, deletion and modification of recoverable objects for subsequent recovery, the computing apparatus including a central processor, one or more non-volatile storage devices (70, 80), and a volatile main storage including a log buffer (60) into which log records are stored for subsequent writing to a journal log on a storage device, the improvement comprising: means (34) for preformatting a write ahead data set on a non-volatile storage device (70) to store a plurality of short data blocks; means (28) responsive to a process epoch occuring before the log buffer is filled for forcing log buffer (60) contents to the write ahead data set; means (24) responsive to the log buffer (60) being filled for writing the log buffer contents to the journal log (80);and means (30) responsive to a system failure resulting in loss of log buffer data not yet purged to the journal log for redoing or undoing data base changes with reference to the write ahead data set, and responsive to a system failure not resulting in the loss of log buffer data not yet written to the journal log for redoing or undoing data base changes with reference to the log buffer or journal log.
Claim 8
Dependent Claim
207 words
A computing apparatus for logging records of the creation, deletion and modification of recoverable objects for subsequent recovery, the computing apparatus including a central processor, one or more non-volatile storage devices (70, 80), and a volatile main storage including a log buffer (60) into which log records are stored for subsequent writing to a journal log on a storage device, the improvement comprising: means (34) for preformatting a write ahead data set on a non-volatile storage device (70) to store a plurality of short data blocks; means (28) responsive to a process epoch occuring before the log buffer is filled for forcing log buffer (60) contents to the write ahead data set; means (24) responsive to the log buffer (60) being filled for writing the log buffer contents to the journal log (80);and means (30) responsive to a system failure resulting in loss of log buffer data not yet purged to the journal log for redoing or undoing data base changes with reference to the write ahead data set, and responsive to a system failure not resulting in the loss of log buffer data not yet written to the journal log for redoing or undoing data base changes with reference to the log buffer or journal log.
References Cited (Backward Citations)
No citation records indexed.
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