Browse Prior Art Database

Intelligent Read Pre-Fetch Function

IP.com Disclosure Number: IPCOM000015333D
Original Publication Date: 2001-Oct-17
Included in the Prior Art Database: 2003-Jun-20
Document File: 1 page(s) / 35K

Publishing Venue

IBM

Abstract

Disclosed is a method to improve performance by modification of LookAhead cache algorithm for HDD (Hard Disk Drive).

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This is the abbreviated version, containing approximately 100% of the total text.

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Intelligent Read Pre-Fetch Function

   Disclosed is a method to improve performance by modification of
LookAhead cache
algorithm for HDD (Hard Disk Drive).

Cache size of HDD is very smaller than HDD capacity. So we need
to increase
efficiency of cache memory usage. We realize it with "dynamic
lookahead length".

For example, almost of lookahead data will not use in random
access. But almost of
lookahead data will use in sequential access. So it can predicte
how many sectors
should be lookahead. The following are rules how to change
"dynamic lookahead length".

If the requested data is already in cache, the data should not be re-read.


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Lookahead length is changed by host requested block.

Relation between "lookahead length" and "host requested block" is dynamically

modified with command analysis table(*) which is updated on every command.

(*) Command analysis table The table prepared to accumulates two data : "Host requested data" and "LBA distance".

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