14 DAY TRIAL // Well-known professional storage solution manufacturer Fusion-io reportedly found a way to make MLC flash NAND behave like SLC cells. Many thought it was a scam, or an expected marketing trick, but it really seems the company’s experts are on to something. Currently, flash NAND-based storage is the fastest popular storage solution available to the IT market.
The problem is the fact that, unlike hard disk drives, flash storage has a limited and quite short life span.
On a hard disk drive (HDD), data can be stored for very long periods of time before it decays. That’s tens of years. It can also be erased and overwritten thousands of times.
On SSDs on the other hand, data can usually be erased and overwritten by about 3000 times for any ordinary drive.
There are premium products that guarantee a 5000 PE cycles, but this is far less than the 30,000 PE cycles SSDs has back in the days NAND was manufactured at 32 nm.
Single level cell NAND (SLC) is known to be considerably faster than multi-level cell NAND (MLC), but the SLC cells are also faster when reading and much faster when being written on. Next to the speed advantage, SLC NAND also has a durability advantage over MLC NAND.
Generally, SLC is up to ten times more durable than MLC. That means that on 25 nm technology, a drive with SLC NAND will last up to 30,000 PE cycles and that’s 1000% more reliable than our popular MLC SSDs.
“A two-bit-per cell has four voltage levels. But you could just ignore the pair for the other bit. So in that sense, you could treat MLC just like SLC, from an engineering standpoint.
“Now you would cut the capacity in half, so you've killed the cost per bit advantage, but there may be other performance advantages to offset that. I don't know if you get any advantage in the PE cycle, but my guess is that you would.
“This seems to be a new line from Fusion-io. And yes, the process is as described. They certainly have the technical capability to do this. I’m still not sold on why,” said Ames Bagley, senior analyst at Storage Strategies Now.
Some other sources also confirmed this while wondering why would Fusion-io introduce such a technology when its own SLC products have much higher profit margins:
“Well it's real. I talked to Fusion guys and they successfully did it. It’s going to commoditize NAND with no need to sell three types. I’m not sure how but they can ‘convert’ commodity MLC to SLC. Flash venders claim you can’t because of different performance profiles. But Fusion claims they’ve done it. And tested it.”
While the price advantage towards the customer is not yet known at this time, we’re happy to see that we’ll get SLC-like performance and durability even if the price stays the same.