How do controllers maximize the life of an SSD? After all, MLC flash has a lifetime of only 10,000 erase/write cycles or fewer and that is a very small number compared to the write traffic an SSD is expected to see in a high-workload environment, especially in the enterprise. Still, MLC is becoming the norm in the enterprise.
How do they do that?
This is where SSD architects really earn their pay. There are eight basic techniques that The SSD Guy knows of to extend SSD life beyond the wear that the flash alone would provide:
- Wear Leveling
- External Data Buffering
- Improved ECC
- Other Error Management
- Reduced Write Amplification
- Over Provisioning
- Feedback on Block Wear
- Internal NAND Management
Each of these is a topic that is complex enough to warrant its own post, so for eight Fridays I published a post on each to explain what each means.
What is important to consider is that the right mix of these techniques allows an SSD to have significantly better wear than the internal NAND’s specifications would support.
Click on any of the above links to learn about how each of these techniques works.
Alternatively, you can visit the Storage Networking Industry Association (SNIA) website to download the entire series as a 20-page booklet in pdf format.