NOTE
Disk
Historical notes comparing the characteristics of disk and memory.
This is a historical learning note and may contain outdated or incomplete understanding.
1. Disk vs. Memory
| Disk | Memory | |
|---|---|---|
| Cost | Low | High |
| Capacity | Large | Small |
| Access speed | Slow; sequential I/O is usually friendlier than random I/O, especially on HDDs | Fast; actual performance is still affected by CPU cache, locality, and other factors |
| Storage characteristic | Data is usually retained after power-off | Data is lost after power-off |
- In general, memory access latency is far lower than persistent storage such as disk. The exact speed relationship depends on HDD / SSD, caches, access patterns, and workload, so it should not be expressed as a fixed equality.
Discussion
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