I understand that both SATA and NVMe drives use flash memory, but I'm unclear about what makes SATA SSDs significantly slower. Do SATA SSDs use different storage technology, or are they mainly limited by the connection and communication protocol used to link them to the computer?
2 Answers
A SATA III connection tops out at 6 gigabits per second, which works out to roughly 550 MB/s in real-world use. NVMe drives typically use multiple PCIe lanes, giving them far more bandwidth and allowing much higher speeds. SATA SSDs are still much faster and less laggy than hard drives because they have no moving parts and much lower access latency.
The underlying flash-storage technology is broadly the same. The major difference is how the drive communicates with the computer: SATA SSDs use the SATA interface and usually the older AHCI protocol, while NVMe drives communicate over PCIe using a protocol designed specifically for solid-state storage. That lets NVMe handle more parallel requests with much lower overhead.
So the main limitation is basically the interface and protocol connecting the drive to the computer, rather than the flash memory itself?