toegangstijd

Toegangstijd, literally “access time” in Dutch, is a concept used in information technology to describe the time from when a request to use a resource is made until the resource is ready for use. In practice, it is a measure of latency and is often discussed in relation to storage systems, memory, or data networks.

In storage devices, toegangstijd covers several components: seek time—the time for the read/write head to position over the correct track; rotational latency—the delay waiting for the correct sector to rotate under the head; and transfer time—the time to move the data off the media once positioned. For hard disk drives (HDDs) these are typically measured in milliseconds. For solid-state drives (SSDs) the seek component is negligible, and access times are often in microseconds.

In RAM and caches, toegangstijd is the time to retrieve a byte or block from a memory location, measured in nanoseconds. Memory hierarchies and caching reduce effective toegangstijd by serving frequently accessed data from faster levels (CPU caches) or adjacent memory.

In broader systems, toegangstijd is an important performance metric for databases, file systems, and networks, affecting perceived responsiveness. It can be influenced by hardware characteristics, queueing, concurrency, and software optimizations such as buffering, prefetching, indexing, and caching strategies.

Measurement and interpretation vary by context. When reporting toegangstijd, it is common to specify the average or worst-case value, the workload, and the hardware involved to allow meaningful comparisons. See also latency, access time, seek time.