[SSD Basic] What is "TBW" and "MTBF"?

These terms relate to an SSD's endurance and reliability.

• TBW (Terabytes Written):
  • Indicates the total amount of data that can be written to the SSD over its lifetime before its endurance limit is reached. It's a measure of the drive's expected lifespan under typical write conditions.
  • For example, an SSD with 300 TBW means you can write 300 terabytes of data to it before it's considered to have reached its rated endurance.
  • This is often correlated with the type of NAND (SLC > MLC > TLC > QLC in terms of TBW) and the drive's capacity (higher capacity drives generally have higher TBW ratings).
• MTBF (Mean Time Between Failures):
  • A statistical measure of the average time or duration of expected operation between failures of a product. It's often expressed in hours (e.g., 1.5 million hours).
  • MTBF is a reliability metric for the entire drive, including its controller and firmware, not just the NAND flash itself. It's a calculated average and doesn't guarantee a specific drive will last that long, but indicates the product's overall reliability in a large population.