EP0682306A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Data storage system and method
Assignee: International Business Machines Corp
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Filing: 1995-05-10
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Granted: —
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Expires: 2015-05-10
Abstract
Abstract A method for operating a disk controller 16 comprises the steps of allocating a first amount of disk space for a compressed data unit as a first predetermined percentage of an uncompressed size of the data unit and increasing the allocation by a second predetermined percentage that is less than the first predetermined percentage to obtain a total amount of allocated disk space.
Inventors
- 👤 James T. Brady
- 👤 Jaishankar M. Menon
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 13:50
CPC Classifications
G; G06; G06F; G06F3/00; G06F3/06; G06F3/0601; G06F3/0602; G06F3/0614; G06F3/0619; G06F3/0628; G06F3/0629; G06F3/0631; G06F3/0668; G06F3/0671; G06F3/0683; G06F3/0689
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
92 words
A data storage system comprising means for compressing a data unit prior to the data unit being written to a disk and a disk controller coupled to the disk for allocating space in the disk for writing a compressed data unit therein, the disk controller including means for comparing a size of a compressed data unit to an amount of space previously allocated for the data unit, and for managing the disk in a log-structured manner when a compressed data unit is larger than the space previously allocated for the data unit.
Claim 2
Dependent Claim
82 words
A data storage system as claimed in claim 1 and further comprising a first buffer for storing an uncompressed data unit and a second buffer for storing the compressed data unit, wherein the disk controller is responsive to a number of bytes in the compressed data unit and in the uncompressed data unit for selectively writing either the content of the first buffer or the second buffer to the disk so as to write the fewest number of bytes to the disk.
Claim 3
Independent Claim
62 words
A method for operating a disk controller, comprising the steps of allocating a first amount of disk space for a compressed data unit as a first predetermined percentage of an uncompressed size of the data unit and increasing the allocation by a second predetermined percentage that is less than the first predetermined percentage to obtain a total amount of allocated disk space.
Claim 4
Dependent Claim
57 words
A method as claimed in claim 3 wherein the first predetermined percentage is a function of an expected compression ratio for the data unit and wherein the second predetermined percentage is a function of an expected change in the size of the compressed data unit as a result of an update operation performed on the data unit.
Claim 5
Dependent Claim
26 words
A method as claimed in claim 3 wherein the first predetermined percentage is approximately 30 percent and wherein the second predetermined percentage is approximately 5 percent.
Claim 6
Dependent Claim
58 words
A method as claimed in claim 3 wherein the first predetermined percentage is based on a most probable data compression ratio for the data unit, and wherein the second predetermined percentage is based on a most probable change in the size of the compressed data unit as a result of an update operation performed on the data unit.
Claim 7
Dependent Claim
110 words
A method as claimed in claim 3 and further including the steps of, compressing the updated data unit in response to an update operation performed on the data unit, comparing the size of the compressed updated data unit to the total amount of allocated disk space and, if the size of the compressed updated data unit is equal to or less than the total amount of allocated disk space, storing the compressed updated data unit within the allocated disk space or, if the size of the compressed updated data unit is greater than the total amount of allocated disk space, allocating other disk space for storing the compressed data unit.
References Cited (Backward Citations)
No citation records indexed.
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