I use a 1 TB KIOXIA-EXCERIA G2 as the boot drive in my daily-use PC. It is rated for 400 TBW and has about 14,000 hours of use. The drive reports roughly 112 TB written by the operating system, but CrystalDiskInfo shows only 48% health. That seems low compared with the advertised endurance, and the health has dropped from around 51% over the past two months. The drive has often been nearly full, although I recently started leaving 200–300 GB free. CrystalDiskInfo shows no media or data integrity errors. Should I replace it immediately, and what could be causing the health percentage to fall so quickly?
3 Answers
Leaving more free space should reduce write amplification, so keeping 20–30% unused is a good habit. However, with available spare still at 100 and the threshold at 5, there is no obvious sign of an immediate hardware failure. Maintain a tested backup, monitor the SMART values and error counters, and plan a replacement when convenient rather than treating this as an emergency.
The health percentage and the host-written total are probably measuring different things. The SSD may have written around 190 TB internally even though the operating system sent it only 112 TB. NAND write amplification from SLC-cache management, garbage collection, and keeping the drive nearly full can account for that difference. A few hundred gigabytes of internal writes per day is not automatically alarming for a busy boot drive with updates, games, and a page file. Since there are no media errors, check the available-spare value and keep current backups rather than replacing the drive solely because of the percentage.
The TBW figure is an endurance estimate, not a precise health meter. The firmware can also reduce the displayed percentage based on internal wear, bad-block replacement, or its own calculation method. Some versions of this drive may even have firmware-reporting quirks involving the endurance rating. A falling health number deserves monitoring, but it does not by itself mean the SSD is about to fail.
The available spare is reported as 100, while the warning threshold is 5.