Redundant array of disk drives with asymmetric mirroring and asymmetric mirroring data processing method
First Claim
1. A method for processing data in data processing system including a redundant array of independent disk drives (RAID) operatively controlled by an array controller comprising the steps of:
- providing a plurality of data drives and a single predefined mirror drive in the RAID;
said single predefined mirror drive having a set capacity substantially greater than a capacity of each of said plurality of data drives;
writing data to multiple data drives in the RAID;
writing a mirror copy of said written data to said predefined mirror drive in the RAID; and
reading data from said multiple data drives.
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Abstract
Apparatus and a method are provided for processing data in data processing system including a redundant array of independent disk drives (RAID) operatively controlled by an array controller. A plurality of data drives and a predefined mirror drive are provided by the RAID. The predefined mirror drive has a set capacity substantially greater than a capacity of each of the plurality of data drives. Data is written to and read from the multiple data drives in the RAID. A mirror copy of the data is written on a predefined mirror drive in the RAID.
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Citations
12 Claims
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1. A method for processing data in data processing system including a redundant array of independent disk drives (RAID) operatively controlled by an array controller comprising the steps of:
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providing a plurality of data drives and a single predefined mirror drive in the RAID;
said single predefined mirror drive having a set capacity substantially greater than a capacity of each of said plurality of data drives;
writing data to multiple data drives in the RAID;
writing a mirror copy of said written data to said predefined mirror drive in the RAID; and
reading data from said multiple data drives. - View Dependent Claims (2, 3, 4, 5)
temporarily storing write command data to a write cache; and
wherein said steps of writing data to multiple data drives and writing a mirror copy to said single predefined mirror drive in the RAID include the step of destaging data from said write cache.
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3. A method for processing data in data processing system including a redundant array of independent disk drives (RAID) as recited in claim 1 wherein said step of reading data from said multiple data drives includes the steps of:
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identifying a busy or failed data drive; and
reading data from said single predefined mirror drive in the RAID.
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4. A method for processing data in data processing system including a redundant array of independent disk drives (RAID) as recited in claim 1 further includes the step of:
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calculating data drives for writing data and identifying a failed data drive;
writing data for said failed data drive to said single predefined mirror drive in the RAID.
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5. A method for processing data in data processing system including a redundant array of independent disk drives (RAID) as recited in claim 2 wherein said step of writing data to multiple data drives in the RAID includes the step of:
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searching the write cache for destage data at higher addresses nearest a drive arm of said single predefined mirror drive;
writing said destage data to said multiple data drives; and
allocating the destage data space in write cache as available.
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6. A data processing system including a redundant array of independent disk drives (RAID) operatively controlled by an array controller, said array controller comprising:
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means for assigning a plurality of data drives and a single predefined mirror drive in the RAID;
said single predefined mirror drive having a set capacity substantially greater than a capacity of each of said plurality of data drives;
means for writing data to said plurality data drives in the RAID;
means for writing a mirror copy of said written data to said single predefined mirror drive in the RAID; and
means for reading data from said multiple data drives. - View Dependent Claims (7, 8, 9, 10)
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11. Apparatus for processing data in data processing system including a redundant array of independent disk drives (RAID) comprising:
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a plurality of data drives in the RAID;
a single predefined mirror drive in the RAID;
said single predefined mirror drive having a predefined capacity greater than or equal to a sum of the capacity of the plurality of data drives;
array controller means for operatively controlling operation of the RAID including;
means for writing data to multiple data drives in the RAID;
means for writing a mirror copy of said written data to said predefined mirror drive in the RAID;
means for reading data from said multiple data drives; and
means for identifying a failed one of said multiple data drive and for reading data from said predefined mirror drive. - View Dependent Claims (12)
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Specification