Writes are not simply single writes in the user or application layers. When you’re thinking about write cycles, also keep write amplification in mind. TLC: Triple-level cells (3-bit) NAND flash is low at 300-1000 write cycles, and can achieve 1500-3000 write cycles with 3D NAND.eMLC (enterprise MLC) sustains up to10,000 write cycles, and can reach 35,000 cycles on 3D NAND. MLC: The 2-bit data multi-level cell ( MLC) flash generally takes up to 3,000 write cycles.SLC: Single-level cell NAND flash supports 50,000 to 100,000 write cycles.The type of cell impacts the number of write cycles before failure. The cause is physical: every time the drive writes/erases, the flash memory cell’s oxide layer deteriorates. NAND flash SSDs have a limited number of write cycles before the cell fails, expressed as its endurance rating. However, SSDs reported more errors than the HDDs, with more bad blocks and uncorrectable errors.

They also reported that Google replaced SSD drives about a quarter less often than HDDs. The study demonstrated that the age of the SSD was the main factor in drive failures. In 2016, Google and University of Toronto reported the results of a joint 4-year study that tracked SSD and HDD reliability in Google’s data-intensive data centers. However, some real-life tests allow us to draw reasonable conclusions. Vendors and users can calculate TBW and DWPD, but some of the numbers are estimates. Of the three, only the age of the drive is a precise measurement.

Total terabytes written over time (TBW).

Throughout the SSD market, SSD vendors rate drive reliability on three factors: If you’re in the market for the best SSDs, see our list of the best and fastest SSDs. As we look at flash storage memory, we’ll discuss how to make those measurements, and how to prolong SSD lifespans. Since most SSDs are made up of NAND flash, the calculations depend on average NAND write cycles. SSD endurance is based on the number of write/erase cycles a flash block can reasonably accept before producing hard errors or complete failure. Solid state drive lifespan is the measure of an SSD drive’s usable lifecycle.

Testing ssd drives for errors