Diskresident

Diskresident is a term used in computing to describe data, programs, or structures that reside on non-volatile disk storage rather than in volatile main memory. The property is often described in contrast to memory-resident or RAM-resident data, which are stored in RAM for fast access. Disk-resident data must be loaded into memory, often through I/O operations, before it can be actively processed.

In operating systems, file systems, and databases, many objects are disk-resident by default, including files, tables, indexes, and large objects. Large datasets or programs that exceed available RAM are kept on disk and paged in as needed. Some systems use memory-mapped I/O to present disk-resident regions as addressable memory, letting the OS handle paging.

Advantages and trade-offs: disk-resident storage provides persistence, capacity, and durability; disadvantages include higher latency and lower bandwidth compared with RAM, requiring caching, buffering, and indexing. Performance depends on hardware, disk speed, and the effectiveness of the OS's paging or the database's buffer pool.

In practice, disk-residence is ubiquitous in modern computing; the term is primarily used to emphasize the location of data and the implications for access speed and durability.