US5623701A
Expired / Lapsed
US
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Data compression method and structure for a direct access storage device
Assignee: HGST Netherlands BV
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Filing: 1995-06-06
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Granted: 1997-04-22
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Expires: 2015-06-06
Abstract
Abstract A data compression method and compression data structure are provided for a direct access storage device (DASD). The DASD is segmented into a plurality of compression groups. Each of the compression groups has a fixed logical size. A directory table is written within each of the compression groups. Each compression group has at least one compressed data region on which compressed data can be written and an exception region on which compressed data exceptions can be written. The compressed data exceptions include updated compressed data which exceeds an original storage space for corresponding original compressed data.
Inventors
- 👤 Brian E. Bakke
- 👤 Daniel F. Moertl
- 👤 Bruce M. Walk
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 14:16
CPC Classifications
G; G06; G06F; G06F3/00; G06F3/06; G06F3/0601; G06F3/0602; G06F3/0608; G06F3/061; G06F3/0611; G06F3/0628; G06F3/0638; G06F3/064; G06F3/0668; G06F3/0671; G06F3/0673; G06F3/0674; G06F3/0676; G11; G11B; G11B20/00; G11B20/00007; Y; Y10; Y10S; Y10S707/00; Y10S707/99941; Y10S707/99942
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
130 words
A method for storing compressed data in a direct access storage device (DASD) of the type including a fixed block architecture comprising the steps of: segmenting the DASD into a plurality of compression groups; each of said compression groups having a fixed logical size; allocating at least one compressed data region and an exception region within each compression group; writing and reading related compressed data to and from said at least one compressed data region of one of said plurality of compression groups; writing and reading compressed data exceptions to and from said exception region; said compressed data exceptions including updated compressed data which exceeds an original storage space for corresponding original compressed data; and writing a corresponding directory table within said exception region for each of said compression groups.
Claim 2
Independent Claim
130 words
A method for storing compressed data in a direct access storage device (DASD) of the type including a fixed block architecture comprising the steps of: segmenting the DASD into a plurality of compression groups; each of said compression groups having a fixed logical size; allocating at least one compressed data region and an exception region within each compression group; writing and reading related compressed data to and from said at least one compressed data region of one of said plurality of compression groups; writing and reading compressed data exceptions to and from said exception region; said compressed data exceptions including updated compressed data which exceeds an original storage space for corresponding original compressed data; and writing a corresponding directory table within said exception region for each of said compression groups.
Claim 3
Dependent Claim
44 words
A method for storing compressed data as recited in claim 1 wherein said step of writing related compressed data to said at least one compressed data region includes the steps of compressing data received from a host computer and identifying a compressed data length.
Claim 4
Dependent Claim
51 words
A method for storing compressed data as recited in claim 2 wherein said step of writing related compressed data to said at least one compressed data region includes the steps of identifying one of said compression groups utilizing a host logical block address for the data received from the host computer.
Claim 5
Dependent Claim
65 words
A method for storing compressed data as recited in claim 1 wherein said step of writing related compressed data to said at least one compressed data region includes the steps of calculating a DASD logical block address utilizing a compression group directory and said host logical block address, calculating a DASD number of blocks using said compression group directory and said identified compressed data length.
Claim 6
Dependent Claim
99 words
A method for storing compressed data as recited in claim 1 wherein said step of writing compressed data exceptions to said exception region includes the steps of: compressing data received from a host computer and identifying a compressed data length; identifying one of said compression groups utilizing a host logical block address for the data received from the host computer; calculating a DASD exception region logical block address utilizing a compression group directory and said host logical block address, and calculating a DASD exception region number of blocks using said compression group directory and said identified compressed data length.
Claim 7
Dependent Claim
42 words
A method for storing compressed data as recited in claim 1 further includes the steps of periodically performing a background sweep operation to correct fragmentation within an identified compression group, said fragmentation resulting from compressed data exceptions written to the exception region.
Claim 8
Dependent Claim
108 words
A method for storing compressed data as recited in claim 6 wherein said steps of performing a background sweep operation includes the steps of: identifying an amount of DASD physical space required for the compression group utilizing an original compression group directory, generating a new compression group directory with all compressed data of said identified compression group reordered in ascending host logical block address sequence with said exception region being empty in a new compression group; utilizing said original compression group directory to gather all data in said identified compression group; and utilizing said generated new compression group directory to store all data in said new compression group.
Claim 9
Dependent Claim
93 words
A direct access storage device for storing a compression data structure, said compression data storage comprising: a plurality of compression groups; each of said compression groups having a fixed logical size; a directory table written within each of said compression groups; each compression group having at least one compressed data region on which compressed data can be written; and each compression group having an exception region on which compressed data exceptions can be written; said compressed data exceptions including updated compressed data which exceeds an original storage space for corresponding original compressed data.
Claim 10
Dependent Claim
93 words
A direct access storage device for storing a compression data structure, said compression data storage comprising: a plurality of compression groups; each of said compression groups having a fixed logical size; a directory table written within each of said compression groups; each compression group having at least one compressed data region on which compressed data can be written; and each compression group having an exception region on which compressed data exceptions can be written; said compressed data exceptions including updated compressed data which exceeds an original storage space for corresponding original compressed data.
Claim 11
Dependent Claim
20 words
A direct access storage device as recited in claim 8 wherein said compression group includes a plurality of compression pages.
Claim 12
Dependent Claim
25 words
A direct access storage device as recited in claim 8 wherein said compression pages have a logical size equal to a host system page size.
Claim 13
Dependent Claim
26 words
A direct access storage device as recited in claim 8 wherein each of said at least one compressed data region includes a fixed number of sectors.
Claim 14
Dependent Claim
28 words
A direct access storage device as recited in claim 9 wherein each of said at least one compressed data region includes a variable number of said compression pages.
Claim 15
Dependent Claim
18 words
A direct access storage device as recited in claim 2 wherein said exception region contains said directory table.
Claim 16
Dependent Claim
26 words
A direct access storage device as recited in claim 8 wherein said compression group contains a variable number of said at least one compressed data regions.
Claim 17
Dependent Claim
18 words
A direct access storage device as recited in claim 9 wherein said compression pages span adjacent compression regions.
Claim 18
Dependent Claim
33 words
A direct access storage device as recited in claim 10 wherein said compression group size includes 1 MB with said compression page logical size and said host system page size of 4 KB.
Claim 19
Independent Claim
173 words
A system for reading and writing compressed data comprising: a host computer for providing and receiving data to a direct access storage device, said host computer including a direct access storage device storage management function and a logical directory for storing logical block addresses; a storage controller coupled to said host computer for receiving and compressing data and writing compressed data to the direct access storage device and for reading and decompressing compressed data from the direct access storage device and providing the data to said host computer; said direct access storage device including a plurality of compression groups; each of said compression groups having a fixed logical size; a directory table written within each of said compression groups; each compression group having at least one compressed data region on which compressed data can be written; and each compression group having an exception region on which compressed data exceptions can be written; each of said compressed data exceptions including updated compressed data which exceeds an original storage space for corresponding original compressed data.
Claim 20
Independent Claim
173 words
A system for reading and writing compressed data comprising: a host computer for providing and receiving data to a direct access storage device, said host computer including a direct access storage device storage management function and a logical directory for storing logical block addresses; a storage controller coupled to said host computer for receiving and compressing data and writing compressed data to the direct access storage device and for reading and decompressing compressed data from the direct access storage device and providing the data to said host computer; said direct access storage device including a plurality of compression groups; each of said compression groups having a fixed logical size; a directory table written within each of said compression groups; each compression group having at least one compressed data region on which compressed data can be written; and each compression group having an exception region on which compressed data exceptions can be written; each of said compressed data exceptions including updated compressed data which exceeds an original storage space for corresponding original compressed data.
Claim 21
Dependent Claim
33 words
A system for reading and writing compressed data as recited in claim 17 wherein said storage controller includes a compression group directory cache and receives a logical block address from said host computer.
Claim 22
Dependent Claim
41 words
A system for reading and writing compressed data as recited in claim 18 wherein said storage controller includes compression management logic for identifying a logical block address within said direct access storage device utilizing said received host computer logical block address.
Claim 23
Dependent Claim
43 words
A system for reading and writing compressed data as recited in claim 17 further includes means for periodically performing a background sweep operation to correct fragmentation within an identified compression group, said fragmentation resulting from compressed data exceptions written to the exception region.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-04-21 | 2000-10-21 | 2001-04-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-04-21 | 2004-10-21 | 2005-04-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-04-21 | 2008-10-21 | 2009-04-22 | $7700.00 | Window Closed / Lapsed |