Browse Prior Art Database

Cache System for Hard Disk System Utilizing the Access Data Address

IP.com Disclosure Number: IPCOM000114644D
Original Publication Date: 1995-Jan-01
Included in the Prior Art Database: 2005-Mar-29
Document File: 4 page(s) / 102K

Publishing Venue

IBM

Related People

Munetoh, S: AUTHOR [+4]

Abstract

Disclosed is a cache system for hard disk system. The cache system manages buffers constructing cache by small unit (From some sectors to some tens sectors. Names "line" in the following). Each line has the address corresponded with the address of the access data, and saves data of the corresponded address. For long data, consecutive lines are concatenated to store the long data.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Cache System for Hard Disk System Utilizing the Access Data Address

      Disclosed is a cache system for hard disk system.  The cache
system manages buffers constructing cache by small unit (From some
sectors to some tens sectors.  Names "line" in the following).  Each
line has the address corresponded  with the address of the access
data, and saves data of the corresponded address.  For long data,
consecutive lines are concatenated to store the long data.

      Fig. 1 shows the example of the Hard Disk Drive (HDD) system
using this invention.  This HDD system consists of Bus IF with host
system's I/O bus, MCU, ROM, RAM, DMAC, Cache, and HDDs.  Cache
consists of Buffer and Tag.  Buffers save data.  Tags record the
properties of the data saved in Buffer.  Cache is controlled by MCU
or special hardware.

      Fig. 2 shows the structure of cache using this invention.
Cache shown by Fig. 2 consists of one way.  Way consists of set of
lines and corresponding Tags.  It is possible to configure the cache
as set-associtive fashion.

      Buffer is divided into lines.  A Tag is corresponded with each
line.  Tag consists of valid flag, dirty flag, top flag, LBA,
Len/top, Offset in Line, and Len in Line.  Valid flag shows whether
the content of Tag is valid or not.  Clean flag shows whether  the
content of the corresponding Line is same as data on HDD or updated
in only Line.  Top flag shows whether the content of the
corresponding Line saves the top of data or not.  LBA records the
higher bits of the top data address saved in the corresponding line.
Len records the length of the data saved in the corresponding line.
Offset in Line shows the location in the line of the top of the data.
Len in Line shows t...