/nænd/
n. “The flash memory building block that stores bits without power.”
NAND is a type of non-volatile flash memory commonly used in SSD drives, USB drives, memory cards, and embedded storage. The term comes from the logic gate “NOT AND,” which forms the basis of its internal architecture. NAND memory retains data even when the power is turned off, making it ideal for persistent storage in modern electronics.
Key characteristics of NAND include:
- Non-Volatile: Stores data without requiring power.
- Block-Based Storage: Data is written and erased in blocks rather than individual bits, which affects performance and endurance.
- High Density: Allows storing large amounts of data in a small physical space.
- Endurance: NAND cells wear out after a certain number of program/erase cycles, requiring wear-leveling algorithms in SSDs.
- Cost-Effective: Less expensive per bit compared to other non-volatile memory types like NOR flash.
A simplified conceptual example of NAND usage in an SSD:
# Writing data to an SSD (Linux example)
dd if=/dev/zero of=/mnt/ssd/testfile bs=1M count=100
# Data is stored in NAND flash cells internally
# SSD controller manages block writing, wear-leveling, and error correctionConceptually, NAND is like a library of tiny lockers: each block can hold many bits of data, and the library keeps track of which lockers are available, which need maintenance, and which are in use.
In essence, NAND flash is the fundamental technology behind modern persistent storage devices, enabling fast, compact, and power-efficient memory for everything from smartphones to enterprise SSDs.