# backing store

> computer storage device, usually a disk, that provides additional storage space for information so that it can be accessed and referred to when required and may be copied into the processor if needed

**Wikidata**: [Q115688409](https://www.wikidata.org/wiki/Q115688409)  
**Source**: https://4ort.xyz/entity/backing-store

## Summary
Backing store is a form of auxiliary memory that provides additional computer storage space, typically using disks, allowing information to be accessed when needed and potentially copied to the processor.

## Key Facts
- Backing store is a subclass of auxiliary memory.
- It is defined as a computer storage device, usually a disk, providing additional storage space.
- Information stored on backing store can be accessed and referred to when required.
- Data on backing store may be copied into the processor if needed.
- Backing store is also known as "backing storage".
- It has 1 sitelink recorded.
- It has a Wikipedia entry in the Irish (ga) language.

## FAQs
### Q: What is the primary purpose of a backing store?
A: The primary purpose is to provide additional, non-volatile storage space for information that needs to be accessed later, supplementing the computer's primary memory.

### Q: How does backing store differ from primary memory (RAM)?
A: Backing store is auxiliary memory (non-volatile, like a disk), accessed via I/O channels, while primary memory (RAM) is volatile, directly accessible by the CPU, but typically smaller and temporary.

### Q: Why might data from backing store need to be copied into the processor?
A: Data may be copied into the processor's primary memory (or cache) for faster access when the CPU needs to actively use it, as disk access is significantly slower than CPU operations.

### Q: Is backing store directly accessible by the CPU?
A: No, backing store is part of auxiliary memory, which is not directly accessible by the CPU; it is accessed via input/output (I/O) channels.

## Why It Matters
Backing store is fundamental to modern computing because it solves the critical problem of insufficient primary memory capacity. Since RAM is volatile and relatively small compared to storage needs, backing store provides persistent, high-capacity storage for operating systems, applications, and user data. This separation allows systems to handle vast datasets and large programs by keeping only active data in fast primary memory, while the rest resides on slower, durable backing store. Without backing store, computers would be severely limited in the amount of data they could manage and the complexity of tasks they could perform, rendering many common applications and operating systems infeasible.

## Notable For
- Its role as a non-volatile form of auxiliary memory accessed via I/O channels, distinct from CPU-accessible primary memory.
- Being a subclass of auxiliary memory, embodying the characteristic of providing persistent storage beyond the CPU's immediate access.
- Typically utilizing disk-based storage technology to achieve its capacity and persistence goals.
- Acting as the essential storage layer where data resides when not actively being processed by the CPU.
- Serving as the primary solution for overcoming the finite and volatile nature of primary memory (RAM) in computer systems.

## Body
### Definition
Backing store is a computer storage device, usually implemented as a disk (like a hard disk drive or solid-state drive), designed to provide additional storage space for digital information.

### Functionality
- It stores information that can be accessed and referred to when required.
- Data stored on backing store may be copied into the processor's primary memory (RAM) if the CPU needs to actively use it.

### Relationship to CPU
- Backing store is **not directly accessible by the CPU**.
- It is part of **auxiliary memory**, which is accessed via input/output (I/O) channels.
- This distinguishes it from primary memory (RAM), which is volatile memory directly accessible by the CPU.

### Classification
- **Aliases**: Backing storage.
- **Subclass Of**: Auxiliary memory.