Storage method and hierarchical padding structure for direct access storage device (DASD) data compression
First Claim
1. A data compression hierarchical padding structure for a computer readable direct access storage device (DASD) using fixed block architecture (FBA) comprising:
- storage, wherein said storage contains at least one compression group;
each compression group having a fixed logical size including a selected number of compressed data pages with an initial page allocation of a number of sectors;
each compression group having a selected minimum page allocation defining a minimum number of sectors allocated for each logical compressed data page; and
each compression group having a selected number of additional padding sectors;
said padding sectors being distributed to said selected number of compressed data pages.
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Abstract
A data compression storage method and data compression hierarchical padding structure are provided for a direct access storage device (DASD) using fixed block architecture (FBA). A minimum page allocation defining a minimum number of sectors allocated for each logical compressed data page is selected. The DASD is segmented into at least one compression group. Each compression group has a fixed logical size and includes a selected number of DASD compressed data pages with an initial page allocation of a number of sectors. The initial page allocation is greater than or equal to the minimum page allocation. A minimum number of compressed data regions is allocated within each compression group. A selected number of additional compressed data regions including a plurality of sectors for padding is allocated within each compression group. The plurality of padding sectors are distributed between the compression pages. An exception region is allocated within each compression group. Compressed data is written to a selected DASD compressed data page and typically updated in place. Compressed data is written and updated to the selected DASD compressed data page using sector borrowing of available free sectors from adjacent pages if needed.
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Citations
24 Claims
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1. A data compression hierarchical padding structure for a computer readable direct access storage device (DASD) using fixed block architecture (FBA) comprising:
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storage, wherein said storage contains at least one compression group; each compression group having a fixed logical size including a selected number of compressed data pages with an initial page allocation of a number of sectors; each compression group having a selected minimum page allocation defining a minimum number of sectors allocated for each logical compressed data page; and each compression group having a selected number of additional padding sectors;
said padding sectors being distributed to said selected number of compressed data pages. - View Dependent Claims (2, 3, 4, 5)
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6. A method for storing compressed data in a direct access storage device (DASD) using fixed block architecture (FBA) comprising the computer executable steps of:
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selecting a minimum page allocation to define a minimum number of sectors allocated for each logical compressed data page; segmenting the DASD into at least one compression group;
each compression group having a fixed logical size and including a selected number of compressed data pages with an initial page allocation of a number of sectors;
said initial page allocation being greater than or equal to said minimum page allocation;allocating a minimum number of compressed data regions within each compression group; allocating a selected number of additional compressed data regions including a plurality of sectors for padding within each compression group; distributing said plurality of padding sectors between said compressed data pages; allocating an exception region within each compression group; and writing compressed data and updated compressed data to a selected compressed data page. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for storing compressed data in a direct access storage device (DASD) using fixed block architecture (FBA) comprising the computer executable steps of:
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selecting a minimum page allocation to define a minimum number of sectors allocated for each logical compressed data page; segmenting the DASD into at least one compression group;
each compression group having a fixed logical size;allocating a selected number of compressed data pages with an initial page allocation of a number of sectors within each compression group;
said initial page allocation being greater than or equal to said minimum page allocation;distributing a selected number of padding sectors to said selected number of compressed data pages; and when writing compressed data to a selected compressed data page, dynamically using said padding sectors and available extra sectors from adjacent compressed data pages.
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16. A computer program product for use in a computer system having a processor, and a direct access storage device (DASD) using fixed block architecture (FBA), the computer program product comprising:
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a computer readable recording medium; means, recorded on the recording medium, for selecting a minimum page allocation to define a minimum number of sectors allocated for each logical compressed data page; means, recorded on the recording medium, for segmenting the DASD into at least one compression group;
each compression group having a fixed logical size and including a selected number of compressed dam pages with an initial page allocation of a number of sectors; and
having a selected number of additional padding sectors;
said padding sectors being distributed to said selected number of compressed data pages; andmeans, recorded on the recording medium, for writing compressed data and updated compressed data to a selected compressed data page. - View Dependent Claims (17, 18, 19)
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20. A computer readable storage device, comprising:
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storage, wherein said storage contains at least one compression group; each compression group having a fixed logical size including a selected number of compressed data pages with an initial page allocation of a number of sectors; each compression group having a selected minimum page allocation defining a minimum number of sectors allocated for each logical compressed data page; and each compression group having a selected number of additional padding sectors;
said padding sectors being distributed to said selected number of compressed data pages. - View Dependent Claims (21, 22, 23, 24)
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Specification