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EP0519670A2
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Apparatus for maintaining fault tolerance in a disk drive array
Assignee: International Business Machines Corp
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Filing: 1992-06-15
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Granted: —
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Expires: 2012-06-15
Abstract
Abstract Fault tolerance in a redundant array 13 of disk drives 20, 21, 22, 23, 24 is degraded when errors exist in the array. Data in the array is rebuilt to remove the degradation, either for entire disk drives or for partial data, with minimal impact on array resources. Rebuilding occurs during idle time of the array or is interleaved between current data area accessing operations of the array at a rate which is inversely proportional to the activity level of the array. Alternatively, data is rebuilt when a data area being accessed is in need of rebuilding. <IMAGE>
Inventors
- 👤 Spencer Wah-Fung Ng
- 👤 David William Palmer
- 👤 Richard Scott Thompson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 21:37
CPC Classifications
G; G06; G06F; G06F11/00; G06F11/07; G06F11/08; G06F11/10; G06F11/1076; G06F11/1092; G06F3/00; G06F3/06; G11; G11B; G11B20/00; G11B20/10; G11B20/18; G11B20/1833
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
105 words
A method of automatically maintaining fault tolerance in a parity array (13) consisting of a plurality of disk drives (20, 21, 22, 23, 24), comprising the machine-executed steps of: detecting a degradation in the fault tolerance of the parity array; evaluating the current information handling activity of the parity array; establishing a plurality of data rebuild methods for removing the fault tolerance degradation from the parity array; and analyzing the current information handling activity of the parity array and selecting one of the plurality of rebuild methods to ensure that the performance of said current information handling activity is not degraded below a predetermined level.
Claim 2
Dependent Claim
55 words
A method as claimed in claim 1, wherein one of said plurality of data rebuild methods comprises the machine-executed steps of: measuring the rate of machine operations of the array; establishing the rate of rebuilding data affected by the error in inverse proportion to the measured rate of machine operations; and rebuilding the data accordingly.
Claim 3
Dependent Claim
50 words
A method as claimed in claim 1 or 2, wherein one of said plurality of data rebuild methods comprises the machine-executed steps of: detecting that the parity array is idle; detecting that one of of the disk drives is affected by error; rebuilding the data during said detected idle times.
Claim 4
Dependent Claim
54 words
A method as claimed in claim 3 as dependent on claim 2, further comprising the machine-executed steps of: completing a data rebuild using the rebuild method of claim 2; detecting that the parity array is idle; and continuing the data rebuilding of additional addressable error-affected data so long as the parity array is idle.
Claim 5
Independent Claim
71 words
A method as claimed in any of claims 1 to 4, where one of said plurality of data rebuild methods comprises the machine-executed steps of: performing a data area access operation to an addressable data unit in the parity array; while performing the data area access operation, detecting that the addressed data unit is affected by error and in need of a data rebuild; rebuilding the addressable data unit being accessed.
Claim 6
Dependent Claim
98 words
Apparatus for automatically maintaining fault tolerance in a parity array (13) consisting of a plurality of disk drives (20, 21, 22, 23, 24), the apparatus comprising: means for detecting a degradation in fault tolerance in the parity array such that one of the disk drives needs to have data rebuilt; means for measuring a rate of machine operations of said array; means responsive to said measured operations rate for establishing a rate of rebuilding for the array for recovering from said degradation; and a plurality of data rebuild means for performing data rebuild in said one disk drive.
Claim 7
Dependent Claim
38 words
Apparatus as claimed in claim 6, further comprising: control means (11) for controlling access to the disk drives in the parity array and for detecting when the array is currently not being accessed for a data handling operation.
Claim 8
Dependent Claim
60 words
Apparatus as claimed in claim 7, wherein one of said plurality of data rebuild means is connected to said control means and to said rate establishing means for determining whether a rebuild can be scheduled, and if so, activating the control means to give access to the parity array to perform a series of rebuild operations at the established rate.
Claim 9
Dependent Claim
60 words
Apparatus as claimed in claim 8, wherein said rate establishing means further comprises: means for indicating a plurality of rebuild rates, each corresponding to predetermined ranges of machine operations rates and in inverse proportion to the operations rate; and means for indicating one of said plurality of rebuild rates as said established rate corresponding to the current machine operations rate.
Claim 10
Dependent Claim
51 words
Apparatus as claimed in claim 7, 8 or 9, wherein one of said plurality of data rebuild means is connected to said control means and responsive to the parity array not being currently accessed to activate the control means to give access to the parity array to perform a data rebuild.
Claim 11
Dependent Claim
49 words
Apparatus as claimed in any of claims 7 to 10, wherein one of said plurality of data rebuild means is connected to the control means and responsive to a disk drive access occurring in an area of the array that needs a data rebuild to perform a data rebuild.
Claim 12
Dependent Claim
44 words
Apparatus as claimed in any of claims 7 to 11, wherein each of the data rebuild means upon completing a data rebuild operation is responsive to the control means indicating no current access or no pending access requests to initiate another data rebuild operation.
References Cited (Backward Citations)
No citation records indexed.
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