apanese researchers showcase hybrid SSD using NAND and ReRAM

The technology inside that new solid state drive you just purchased could be obsolete sooner than you think. A group of Japanese researchers have developed ahybrid SSD that uses high-capacity NAND flash memory alongside Resistive Random Access Memory, or ReRAM. The combination could allow future drives to write up to eleven times faster than today’s quickest SSDs.

The research was led by Professor Ken Takeuchi from Chuo University and presented at the 2012 Symposium of VLSI Circuits held in Hawaii. At the event, the group proposed a drive that included 256GB of NAND flash as well as 8 Gbits of ReRAM, the latter of which is used as cache and storage.

In addition to the increased speeds, researchers claim the hybrid drive will reduce power consumption by up to 93 percent. And if that isn’t enough to get you excited, these drives could last far longer than traditional SSDs – nearly seven times longer, to be exact. ReRAM, however, is currently expensive but the price versus longevity factor could reduce overall costs to just 1/7 of today’s drives.

Life of the drive is also extended by reducing the number of writes in the NAND flash. Instead, data is written in the ReRAM about 30 times more often than in NAND flash.

An algorithm called MRU (most recently used) is used to store frequently used data in the ReRAM. By using this method, common data can be read from the drive faster than from NAND flash.

Despite its promise, Neowin concludes that we aren’t likely to see this technology come to consumer-level SSDs anytime soon. The reason for this has to do with the price of ReRAM. If the researchers can significantly lower the overall price (none was mentioned) then things could become much more feasible.

OCZ moves to 25nm NAND flash, customers are not happy

OCZ Technology today announced it is the first solid-state drive manufacturer to complete the transition to 2Xnm NAND flash-based storage solutions. Specifically, the company is using 25nm NAND flash chips from Micron, which take up less space and allow for (eventually) larger capacity SSDs than current 34nm chips, while also costing around 10-15% less.

The smaller chips began to appear in Vertex 2 and Agility 2 drives last week, but so far there hasn't been any significant price cuts from retailers that we know of nor OCZ is making a clear distinction between 25nm and 34nm SSDs. What some unsuspecting buyers did find out, however, is that usable capacities on the newer drives have actually dropped.

Storage Reviews explains the reason behind this in a recent article and essentially it all comes down to the lifespan of 25nm chips. You see, 25nm NAND is 'good' for 3,000 write cycles, while the older 34nm NAND reaches 5,000 cycles, so to account for this drop in individual cell lifespan OCZ needs to increase the amount of reserve capacity that replaces worn sections as the drive degrades. As a result, newer drives are getting around 4-5GB less of usable storage space compared to the same models equipped with 34nm -- which is pretty critical when you are getting a 40GB boot drive.

Besides the reduction in usable storage space, the problem would get even more frustrating for customers looking to setup a RAID 0, 1 or 5 array only to find out that they have drives with mismatching capacities.

We should note that this issue is not exclusive to OCZ, and as other manufacturers start releasing 2Xnm drives we will likely see a similar drop in usable storage space to allow for warranties and expected life spans to stay the same. However, there is something to be said about the lack of transparency when it comes to usable capacity and OCZ's failure to clearly label which version you are buying -- after all, customers are getting less space for the same price and performance, while OCZ presumably nets higher profits with the reduced cost of the smaller 25nm flash.

We hope OCZ takes serious issue with this but so far the only solution offered is for displeased buyers to ship back their 25nm drive and "receive a credit towards the more expensive 32 Gbit die‐based drives.