RAID apparatus and logical device expansion method thereof
First Claim
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1. A RAID apparatus for separating data according to a RAID configuration definition and reading/writing the data from/to a plurality of physical disk devices in parallel, comprising:
- a control unit for accessing said plurality of physical disk devices according to RLU (RAID logical unit) mapping based on said RAID configuration definition upon an I/O request from a host device;
a table for storing old RAID configuration definition information which defines at least an old RAID level and a number of old logical devices, and new RAID configuration definition information which defines at least a new RAID level and a number of new logical devices; and
a cache memory for temporarily storing data for changing the old RAID configuration to the new RAID configuration,wherein said control unit reads out the data from said plurality of physical disk devices to said cache memory according to the RAID logical unit mapping based on said old RAID configuration definition of said table, and writes the data which was read out to said cache memory to said plurality of physical disk devices according to the RAID logical unit mapping based on said new RAID configuration definition of said table in an active status.
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Abstract
A RAID device changes the redundancy of the RAID configuration, while allows various RAID level conversions and capacity increase. Using new and old RAID configuration definition information which define at least a RAID level and a number of logical devices, the control unit performs RLU mapping based on the respective RAID configuration definition information, and performs staging and write back to change the RAID configuration. Therefore various RAID level conversions and capacity increase can be implemented.
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20 Claims
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1. A RAID apparatus for separating data according to a RAID configuration definition and reading/writing the data from/to a plurality of physical disk devices in parallel, comprising:
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a control unit for accessing said plurality of physical disk devices according to RLU (RAID logical unit) mapping based on said RAID configuration definition upon an I/O request from a host device; a table for storing old RAID configuration definition information which defines at least an old RAID level and a number of old logical devices, and new RAID configuration definition information which defines at least a new RAID level and a number of new logical devices; and a cache memory for temporarily storing data for changing the old RAID configuration to the new RAID configuration, wherein said control unit reads out the data from said plurality of physical disk devices to said cache memory according to the RAID logical unit mapping based on said old RAID configuration definition of said table, and writes the data which was read out to said cache memory to said plurality of physical disk devices according to the RAID logical unit mapping based on said new RAID configuration definition of said table in an active status. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A logical device expansion method for a RAID apparatus which separates data according to a RAID configuration definition and reads/writes the data to a plurality of physical disk devices in parallel, comprising the steps of:
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reading out the data from said plurality of physical disk devices to a cache memory according to an RLU (RAID logical unit) mapping based on an old RAID configuration definition information which defines at least an old RAID level and a number of old logical devices; and writing the data which was read out to said cache memory to said plurality of physical disk devices according to an RAID logical unit mapping based on a new RAID configuration definition information which defines at least a new RAID level and a number of new logical devices, wherein said reading and writing are executed in an active status. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification