US6282671B1
Expired / Lapsed
US
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Method and system for improved efficiency of parity calculation in RAID system
Assignee: International Business Machines Corp
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Filing: 1998-11-10
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Granted: 2001-08-28
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Expires: 2018-11-10
Abstract
Abstract The method and system for improved efficiency and parity calculation in RAID data storage system. RAID data storage systems permit recovery of data in the event of a drive failure by storing a parity value for each stripe of data on a separate drive. Each time data is written to a RAID data storage the parity value for the associated data stripe must be updated. Parity may be calculated utilizing two different algorithms. New parity may be calculated utilizing the old data value, the new data value and the old parity value, or calculated utilizing the new data value and all remaining old data within the associated data stripe. The number of input/output operations required to calculate parity utilizing each algorithm is predetermined and the method requiring the least number of input/output operations is selected, unless data sequentiality is detected. If sequential data is present the parity value is calculated utilizing the new data and all old data in the associated data stripe, even if a greater number of input/output operations are initially required, as further sequential input/output operations will be more efficient.
Inventors
- 👤 Shah Mohammad Rezaul Islam
- 👤 Linda Ann Riedle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 17:42
CPC Classifications
G; G06; G06F; G06F11/00; G06F11/07; G06F11/08; G06F11/10; G06F11/1076; H; H03; H03M; H03M13/00; H03M13/03; H03M13/05; H03M13/09; G06F2211/00; G06F2211/10; G06F2211/1002; G06F2211/1009; H03M13/13; H03M13/15; H03M13/151; H03M13/1515
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
195 words
A method for improved efficiency of parity calculation in a RAID data storage system having a cache memory, said method comprising the steps of: in response to each writing of updated data to replace old data within said RAID data storage system wherein said updated data does not span an entire data stripe: predetermining a number of input/output operations required to calculate an RMW new parity value utilizing an old parity value; said old data; and, said updated data; predetermining a number of input/output operations required to calculate an XOR new parity value utilizing said updated data and all remaining old data within said entire data stripe; and determining if data sequentially preceding said updated data is present within said cache memory; calculating an RMW new parity value only if calculation of said RMW new parity value requires fewer input/output operations and data sequentially preceding said updated data is not present within said cache memory; and calculating an XOR new parity value if calculation of said XOR new parity value requires fewer input/output operations or said data preceding said updated data is present within said cache memory wherein RAID data storage system performance is optimized.
Claim 2
Independent Claim
195 words
A method for improved efficiency of parity calculation in a RAID data storage system having a cache memory, said method comprising the steps of: in response to each writing of updated data to replace old data within said RAID data storage system wherein said updated data does not span an entire data stripe: predetermining a number of input/output operations required to calculate an RMW new parity value utilizing an old parity value; said old data; and, said updated data; predetermining a number of input/output operations required to calculate an XOR new parity value utilizing said updated data and all remaining old data within said entire data stripe; and determining if data sequentially preceding said updated data is present within said cache memory; calculating an RMW new parity value only if calculation of said RMW new parity value requires fewer input/output operations and data sequentially preceding said updated data is not present within said cache memory; and calculating an XOR new parity value if calculation of said XOR new parity value requires fewer input/output operations or said data preceding said updated data is present within said cache memory wherein RAID data storage system performance is optimized.
Claim 3
Dependent Claim
84 words
The method for improved efficiency of parity calculation in a RAID data storage system, having a cache memory according the claim 1 , wherein said step of calculating an RMW new parity value only if calculation of said RMW new parity value requires fewer input/output operations comprises the step of calculating an RMW new parity value by combining said old parity value in an exclusive OR operation with said old data which had been combined in an exclusive OR operation with said update data.
Claim 4
Dependent Claim
77 words
The method for improved efficiency of parity calculation in a RAID data storage system, having a cache memory according the claim 1 , wherein said step of calculating an XOR new parity value only if calculation of said XOR new parity value requires fewer input/output operations comprises the step of calculating an XOR new parity value by combining in an exclusive OR operation with said update data and all remaining old data within said entire data stripe.
Claim 5
Dependent Claim
46 words
The method for improved efficiency of parity calculation in a RAID data storage system, having a cache memory according the claim 1 , further including the step of storing said RMW new parity value or said XOR new parity value within said RAID data storage system.
Claim 6
Dependent Claim
100 words
The method for improved efficiency of parity calculation in a RAID data storage system, having a cache memory according the claim 1 , wherein said step of predetermining a number of input/output operations required to calculate an RMW new parity value utilizing an old parity value, said old data, and said updated data comprises the step of predetermining a number of input/output operations required to calculate an RMW new parity value utilizing an old parity value, said old data, and, said updated data, by considering whether said old parity value or said old data are present within said cache memory.
Claim 7
Dependent Claim
98 words
The method for improved efficiency of parity calculation in a RAID data storage system, having a cache memory according the claim 1 , wherein said step of predetermining a number of input/output operations required to calculate an XOR new parity value utilizing said updated data and all remaining old data within said entire data strip comprises the step of: predetermining a number of input/output operations required to calculate an XOR new parity utilizing said updated data and all remaining old data within said entire data stripe considering whether said remaining old data is present within said cache memory.
Claim 8
Independent Claim
233 words
The system for improved efficiency of parity calculation in a RAID data storage system having a cache memory, said system comprising: a processor for predetermining a number of input/output operations required to calculate an RMW new parity value utilizing an old parity value; said old data; and, said updated data, in response to each writing of updated data replace old data within said RAID data storage system wherein said updated data does not span an entire data stripe, and for predetermining a number of input/output operations required to calculate an XOR new parity value utilizing said updated data and all remaining old data within said entire data stripe in response to each writing of updated data replace old data within said RAID data storage system wherein said updated data does not span an entire data stripe; a memory controller for determining if data sequentially preceding said updated data is present within said cache memory; and an XOR calculator for calculating an RMW new parity value only if calculation of said RMW new parity value requires fewer input/output operations and data sequentially preceding said updated data is not present within said cache memory, and for calculating an XOR new parity value if calculation of said XOR new parity value requires fewer input/output operations or said data preceding said updated data is present within said cache memory wherein RAID data storage system performance is optimized.
Claim 9
Independent Claim
233 words
The system for improved efficiency of parity calculation in a RAID data storage system having a cache memory, said system comprising: a processor for predetermining a number of input/output operations required to calculate an RMW new parity value utilizing an old parity value; said old data; and, said updated data, in response to each writing of updated data replace old data within said RAID data storage system wherein said updated data does not span an entire data stripe, and for predetermining a number of input/output operations required to calculate an XOR new parity value utilizing said updated data and all remaining old data within said entire data stripe in response to each writing of updated data replace old data within said RAID data storage system wherein said updated data does not span an entire data stripe; a memory controller for determining if data sequentially preceding said updated data is present within said cache memory; and an XOR calculator for calculating an RMW new parity value only if calculation of said RMW new parity value requires fewer input/output operations and data sequentially preceding said updated data is not present within said cache memory, and for calculating an XOR new parity value if calculation of said XOR new parity value requires fewer input/output operations or said data preceding said updated data is present within said cache memory wherein RAID data storage system performance is optimized.
Claim 10
Dependent Claim
86 words
The system for improved efficiency of parity calculation in a RAID data storage system, having a cache memory according the claim 7 , wherein said XOR calculator for calculating an RMW new parity value only if calculation of said RMW new parity value requires fewer input/output operations comprises an XOR calculator for calculating an RMW new parity value by combining said old parity value in an exclusive OR operation with said old data which had been combined in an exclusive OR operation with said update data.
Claim 11
Dependent Claim
79 words
The system for improved efficiency of parity calculation in a RAID data storage system, having a cache memory according the claim 7 , wherein said XOR calculator for calculating an XOR new parity value only if calculation of said XOR new parity value requires fewer input/output operations comprises an XOR calculator for calculating an XOR new parity value by combining in an exclusive OR operation with said update data and all remaining old data within said entire data stripe.
Claim 12
Dependent Claim
47 words
The system for improved efficiency of parity calculation in a RAID data storage system, having a cache memory according the claim 7 , further including a storage controller for storing said RMW new parity value or said XOR new parity value within said RAID data storage system.
Claim 13
Dependent Claim
100 words
The system for improved efficiency of parity calculation in a RAID data storage system, having a cache memory according the claim 7 , wherein said processor for predetermining a number of input/output operations required to calculate an RMW new parity value utilizing an old parity value, said old data, and said updated data comprises a processor for predetermining a number of input/output operations required to calculate an RMW new parity value utilizing an old parity value, said old data; and, said updated data, by considering whether said old parity value or said old data are present within said cache memory.
Claim 14
Dependent Claim
98 words
The system for improved efficiency of parity calculation in a RAID data storage system, having a cache memory according the claim 7 , wherein said processor for predetermining a number of input/output operations required to calculate an XOR new parity value utilizing said updated data and all remaining old data within said entire data strip comprises a processor for: predetermining a number of input/output operations required to calculate an XOR new parity utilizing said updated data and all remaining old data within said entire data stripe considering whether said remaining old data is present within said cache memory.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2004-08-27 | 2005-02-26 | 2005-08-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-08-27 | 2009-02-26 | 2009-08-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-08-27 | 2013-02-26 | 2013-08-28 | $7700.00 | Window Closed / Lapsed |