dcsimg
Main » TERM » D »

disk cache

cache

)A portion of RAM used to speed up access to data on a disk. The RAM can be part of the disk drive itself (sometimes called a hard disk cache or buffer) or it can be general-purpose RAM in the computer that is reserved for use by the disk drive (sometimes called a soft disk cache). Hard disk cachesare more effective, but they are also much more expensive, and therefore smaller. Nearly all modern disk drives include a small amount of internal cache.

A soft disk cache works by storing the most recently accessed data in the RAM cache. When a program needs to access new data, the operating system first checks to see if the data is in the cache before reading it from the disk. Because computers can access data from RAM much faster than from a disk, disk caching can significantly increase performance. Many cache systemsalso attempt to predict what data will be requested next so they can place that data in the cache ahead of time.

Although caching improves performance, there is some risk involved. If the computer crashes (due to a power failure, for example), the system may not have time to copy the cache back to the disk. In this case, whatever changes you made to the data will be lost. Usually, however, the cache system updates the disk frequently so that even if you lose some data, it will not be much. Caches that work in this manner are called write-back caches. Another type of disk cache, called a write-thru cache, removes the risk of losing data because it only caches data for read operations; writeoperations are always sent directly to the disk.










LATEST ARTICLES
Facts about IT & Coding Boot Camps

The following coding and IT boot camp facts and statistics provide an introduction to the changing trends in education and training programs. Read More »

Top Cloud Computing Facts

The following facts and statistics capture the changing landscape of cloud computing and how service providers and customers are keeping up with... Read More »

Texting & Chat Abbreviations

From A3 to ZZZ this guide lists 1,500 text message and online chat abbreviations to help you translate and understand today's texting lingo. Read More »

STUDY GUIDES
Java Basics, Part 1

Java is a high-level programming language. This guide describes the basics of Java, providing an overview of syntax, variables, data types and... Read More »

Java Basics, Part 2

This second Study Guide describes the basics of Java, providing an overview of operators, modifiers and control Structures. Read More »

Network Fundamentals Study Guide

Networking fundamentals teaches the building blocks of modern network design. Learn different types of networks, concepts, architecture and... Read More »