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EP0080878A2
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EP
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Cache memory and method of control for use with magnetic disks
Assignee: Storage Technology Corp
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Filing: 1982-11-26
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Granted: —
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Expires: 2002-11-26
Abstract
Abstract Data from disk units (26) is cached track by track in a cache memory (30) via a control unit (32) and a director (12 or 14). In order to write complete tracks without waiting for the beginning of track index mark, the track position at the start of writing (ascertained by counting bytes from the index mark) Is latched in a first register. A second register is zeroized at the beginning of the track and incremented as bytes are written until the contents of the second register match those of the first. A cache header is assembled from the record headers (R4,R5,R6,R1,R2,R3) found on the track, in the order to writing to the cache memory. A unique byte (Null-74) is Interpolated to mark the track beginning and the cache header terminates with another unique byte (Wrap-72).
Inventors
- 👤 Robert J. Moreno
- 👤 Brian E. Trede
- 👤 Robert W. Schmidt
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 21:33
CPC Classifications
G; G06; G06F; G06F12/00; G06F12/02; G06F12/08; G06F12/0802; G06F12/0866; G06F2212/00; G06F2212/31; G06F2212/312
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
97 words
A cache memory system for use with magnetic disk data storage media (26), a solid-state memory array (30) and controller means (12,32) adapted to maintain information whereby correspondence between data locations on the disk storage media and storage addresses of data records stored in the solid-state array can be maintained, characterised in that the correspondence is established by comparison of an emulated track position, corresponding to the point on a given disk track at which a given data record stored in said cache memory means begins, with the starting address .of said record in said. cache memory.
Claim 2
Dependent Claim
97 words
A cache memory system for use with magnetic disk data storage media (26), a solid-state memory array (30) and controller means (12,32) adapted to maintain information whereby correspondence between data locations on the disk storage media and storage addresses of data records stored in the solid-state array can be maintained, characterised in that the correspondence is established by comparison of an emulated track position, corresponding to the point on a given disk track at which a given data record stored in said cache memory means begins, with the starting address .of said record in said. cache memory.
Claim 3
Dependent Claim
96 words
A system according to claim 1, characterised in that the emulated track position value is stored in a first register at the beginning of writing of data from a disk track into the memory and, when an index mark is detected on the disk track, a second register is initialized to zero and is thereafter incremented upon reading of each byte from the disk track to the memory, whereby the contents of the second : register may be compared to said emulated track position, the values being the same when an entire track has been read.
Claim 4
Independent Claim
160 words
A method of control of a cache memory system adapted to store information received from magnetic disk memory media in quantities equal to the capacity of one disk track, characterised in that the data is read sequentially starting at any position on a given disk track, an emulated track position corresponding to the relative position on the disk at which the data begins to be read into the cache memory is stored in a first register, a second register is set to zero upon detection of an index mark on the disk during reading of data from the disk into the cache memory, the second register is increment upon reading of successive bytes of data, and the contents of the second register are compared with the emulated track position stored in the first register and, when the contents equal the stored emulated track position, an indication is provided that an entire disk track has been read into the cache memory.
Claim 5
Independent Claim
160 words
A method of control of a cache memory system adapted to store information received from magnetic disk memory media in quantities equal to the capacity of one disk track, characterised in that the data is read sequentially starting at any position on a given disk track, an emulated track position corresponding to the relative position on the disk at which the data begins to be read into the cache memory is stored in a first register, a second register is set to zero upon detection of an index mark on the disk during reading of data from the disk into the cache memory, the second register is increment upon reading of successive bytes of data, and the contents of the second register are compared with the emulated track position stored in the first register and, when the contents equal the stored emulated track position, an indication is provided that an entire disk track has been read into the cache memory.
Claim 6
Dependent Claim
67 words
A method according to claim 3, further characterised by the step of writing into a third register header information from the first record read in a given read operation from disk into the cache memory, comparing the contents of the third register with header information stored on the disk as part of records written to the cache memory, and terminating the read operation when correspondence is found.
Claim 7
Dependent Claim
59 words
In a method of staging data stored on disk memory media in logical tracks made up of plural records into a solid state cache memory, characterised by writing identifying header information into the cache memory during the staging, so that the length of the header is proportional to the number of the records comprised in a given disk track.
Claim 8
Dependent Claim
59 words
In a method of staging data stored on disk memory media in logical tracks made up of plural records into a solid state cache memory, characterised by writing identifying header information into the cache memory during the staging, so that the length of the header is proportional to the number of the records comprised in a given disk track.
Claim 9
Dependent Claim
35 words
A method according to claim 5, wherein the header additionally comprises bytes indicative of the point at which an index mark on the disk is detected during the staging of data to the cache memory.
References Cited (Backward Citations)
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