What is Access Method?
An access method is a technique or program code used by computer systems to manage and control access to data storage devices or shared communication channels. In operating systems, access methods like Virtual Storage Access Method (VSAM) and Indexed Sequential Access Method (ISAM) handle formatting and directing data to specific storage devices. In local area networks, access methods like Carrier Sense Multiple Access with Collision Detection (CSMA-CD) and token passing arbitrate the use of the communication medium, granting access selectively to individual stations to prevent data collisions.
Applications of Access Method
- Sequential access: Good for reading data in order, like reading a book. Slow for finding specific data.
- Direct access: Fast for finding specific data (like jumping to a page in a book with an index).
- Indexed access: Balances speed for finding specific data and efficiency for processing large files.
- Random access: Fastest access, allows going to any part of the data directly. Most complex.
- Hashing: Efficient for finding data using a unique identifier but can have collisions.
