Patent US1819694A successfully refreshed from Google Patents.
EP0481759A2
Expired / Lapsed
EP
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Direct access storage device
Assignee: International Business Machines Corp
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Filing: 1991-10-16
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Granted: —
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Expires: 2011-10-16
Abstract
Abstract A method for update writing in an array of DASDs (3) in a reduced number of DASD track cycles. The method involves distributing data and parity blocks for each parity group across the array in failure independent form and reserving unused space. During a first cycle, the old data and parity blocks are read. The new parity is calculated and shadow written into reserved unused space located before the old parity block recurs. The amended data is either written in place during a second cycle or shadow written into reserved space during a subsequent portion of the first cycle.
Inventors
- 👤 Jaishankar Moothedath Menon
- 👤 James Matthews Kasson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 19:03
CPC Classifications
G; G06; G06F; G06F11/00; G06F11/07; G06F11/08; G06F11/10; G06F11/1076; G06F11/1008; G06F3/00; G06F3/06; G06F3/0601; G11; G11B; G11B20/00; G11B20/10; G11B20/18; G11B20/1833; G06F3/0668; G06F3/0671; G06F3/0673
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
132 words
A method for updating information stored in failure independant form on disks in an array of direct access storage devices connected to a data processing system, said information being stored in the form of data blocks and corresponding parity blocks and at least one of said disks including a reserved portion of storage space, said method comprising the steps of: reading a preselected data block from said disks; writing an updated data block onto said disks; reading an original parity block corresponding to said preselected data block during a former part of a disk revolution; calculating a new parity block corresponding to said updated data block; and writing said new parity block onto said reserved portion of storage space during the latter part of said revolution before said original parity block recurs.
Claim 2
Dependent Claim
42 words
A method as claimed in Claim 1, wherein said updated data block is written onto a second reserved portion of storage space after said preselected data block has been read but during the same revolution as said preselected data block was read.
Claim 3
Independent Claim
39 words
A method as claimed in any of the preceding Claims, further comprising the step of: signalling an address table in said data processing system whenever data is updated thereby maintaining a record of available reserved portions and parity blocks.
Claim 4
Independent Claim
22 words
A method as claimed in any of the preceding Claims, wherein each of said disks contain either data blocks or parity blocks.
Claim 5
Independent Claim
40 words
A method as claimed in any of the preceding Claims, wherein said step of calculating a new parity block includes the step of calculating the modulo 2 addition of the original and updated data blocks and the original parity block.
Claim 6
Independent Claim
127 words
A method for updating information stored on a disk in a direct access storage device of a data processing system, said information being stored in the form of data blocks and corresponding parity blocks and said disk including a reserved portion of storage space, said method comprising the steps of: reading a preselected data block on said disk; writing an updated data block onto said disk; reading an original parity block corresponding to said preselected data block during a former part of a revolution of said disk; calculating a new parity block corresponding to said updated data block; and writing said new parity block onto said reserved portion of said disk during the latter part of said revolution of said disk before said original parity block recurs.
Claim 7
Dependent Claim
144 words
A data processing system including an array of direct access storage devices, information being stored in said direct access storage devices in the form of data blocks and corresponding parity blocks and said direct access storage devices including a reserved portion of storage space, said system including: means for reading a preselected data block from disks in said direct access storage device; means for writing an updated data block onto disks in said direct access storage device; means for reading an original parity block corresponding to said preselected data block during a former part of a revolution of said disks; means for calculating a new parity block corresponding to said updated data block; and means for writing said new parity block onto said reserved portion of storage space during the latter part of said revolution of said disks before said original parity block recurs.
Claim 8
Dependent Claim
37 words
A data processing system as claimed in Claim 6 further comprising: means for signalling an address table in said data processing system whenever data is updated, thereby maintaining a record of available reserved portions and parity blocks.
References Cited (Backward Citations)
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