Redundant array of disks with improved storage and recovery speed
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorsToshio Matsumoto, Hiroshi Baba, Kazuhiko Itoh, Shiro Ogura
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Abstract
In a redundant array of disks, the disks are divided into areas of different sizes, so that small amounts of data can be stored in an area of an appropriate size on a single disk, instead of being spread over multiple disks. A usage status table indicates which areas are in use. Check information is generated and stored only for areas indicated to be in use. When new check information is generated, it is therefore possible to omit the reading of unnecessary old data and old check information.
Claims18
A method of storing data in a redundant array of disks, comprising the steps of:
- partitioning said redundant array of disks into a plurality of areas, each area being a portion of one disk of the redundant array of disks, wherein each area has a size which is one of at least two different sizes;
- receiving a command to store a quantity of data in said redundant array;
- selecting at least one area of the plurality of areas so that a sum of the size of the selected at least one area is adequate to store said quantity of data, and the number of the selected at least one area is minimized;
- and
- storing said quantity of data in the selected at least one area.
A redundant array of disks, comprising:
- a plurality of disks for storing data, partitioned into a plurality of areas, each area being a portion of one disk of the redundant array of disks, wherein each area has a size which is one of at least two different sizes;
- a first semiconductor memory for storing new data received from a host computer;
- a second semiconductor memory for storing an area table having a plurality of pointers corresponding to areas of different sizes, among said plurality of areas;
- and
- a microprocessor to refer to said area table to select at least one area of the plurality of areas so that a sum of the size of the selected at least one area is adequate to store said new data, and the number of the selected at least one area is minimized, and to write said new data on the selected at least one area.
Dependencies are inferred from the claim text.