By Jieming Zhu

I will continue on with part 2 now. Hope you enjoy and please share your thoughts!

Claim #3: Because SSD does not use any mechanical moving parts, it's inherently more reliable than HDDs.

This is probably the biggest misnomer surrounding around SSD's enterprise adoption. Quite to the contrary, because of the lack of enterprise usage, the reliability of SSD is unknown and confusing to most users, even vendors. While we have decades of experiences of how to measure, protect and improve the reliability in the HDD world, the work on the SSD side has barely started. Often times, we hear conflicting definitions about MTBF when it comes to SSD. Do you mean useable capacity or raw capacity of an SSD drive? Do you cite the underlying flash chip number or you have done drive level testing/validation? Do customers know that MTBF actually has nothing to the write endurance? Speaking of write endurance, there are so many different parameters that flash vendors tend to tweak to make their numbers better. Every time when we hear a write endurance number, do we know the actual formula used? What's the page size? What's the I/O block size? How are they mapped? In addition to wear-leveling, what about the read disturbance?  How do we handle the bit error? How do we deal with the data retention problem?

Where it matters most, the reliability of enterprise SSD poses many questions, with so few answers...

Don't take me wrong. I am actually a firm believer that SSD, or rather, the general solid state storage technology, brings tremendous performance/cost benefit as well as the energy and space efficiency to data centers. Further more, I also believe that it is a potentially a disruptive technology that will bring some fundamental changes in how storage subsystems are designed, how servers are designed and how OS's and applications should change for the NVRAM access.

As an industry, we have the responsibility to proactively push the technology (we have endless challenges in that front alone!) and responsibly market it to help our customers adopt. Over hyping can only cause the backlash that ultimately hurts us all. It would be particularly a shame for such a promising new technology as SSD.