Access time

Access time is a term used in computer science to describe the time interval between a request for data and the completion of data delivery. It is a key performance metric in computer storage devices such as hard disk drives (HDDs), solid-state drives (SSDs), and random-access memory (RAM).

Overview

Access time is typically measured in milliseconds (ms) or nanoseconds (ns), and it includes both the time to locate the data on the storage medium (seek time) and the time to actually deliver the data (transfer time). Lower access times are generally better, as they mean that data can be accessed more quickly.

Factors Affecting Access Time

Several factors can affect the access time of a storage device. These include the physical characteristics of the device, such as its rotational speed (in the case of HDDs) or its electronic characteristics (in the case of SSDs and RAM). The organization of the data on the device can also affect access time, as can the efficiency of the device's file system.

Access Time in Different Storage Devices

Different types of storage devices have different typical access times. For example, HDDs generally have access times in the range of 5 to 10 ms, while SSDs have access times in the range of 0.1 to 0.5 ms. RAM, which is used for primary storage in computers, has an access time in the range of 50 to 70 ns.

See Also

• Seek time
• Transfer time
• Latency
• Computer performance