SanDisk Announces Entry-Level SSD Plus & Ultra II mSATA

Back in September SanDisk launched the Ultra II for the mainstream market and it’s been doing pretty well in the market so far. Today here at CES SanDisk is announcing a new entry-level member to its client SSD family, which is simply called the SSD Plus. Quite surprisingly, the SSD Plus isn’t based on TLC NAND, but uses SanDisk’s second generation 19nm MLC NAND instead, similar to the high-end Extreme Pro. SanDisk didn’t really go into detail about the hardware itself, so at this point I’m not sure where the cost savings are coming from (perhaps it’s just lower binned MLC). The controller remains a secret too, although given SanDisk’s history I’m pretty confident that it’s a Marvell silicon with SanDisk’s in-house firmware. 

Availability is slated for this quarter (Q1’15) and the SSD Plus will only be available in capacities of 120GB and 240GB due to the entry-level focus. MSRPs are $70 and $110 respective with a warranty of three years. I’m still trying to wrap my head around the technological placement of the SSD Plus as it seems a bit weird to have MLC in the entry-level offering and then TLC in the one level up, but I should have a better understanding of the product once I have a sample on hand.

In addition to the SSD Plus, SanDisk is also announcing an mSATA version of the Ultra II. The core architecture remains unchanged as it’s just a different form factor, although interestingly enough the mSATA flavor features less over-provisioning and is available in capacities of 128GB, 256GB and 512GB (whereas the 2.5″ Ultra II is 120GB, 240GB, etc…). MSRPs are $74, $116 and $221 respectively and availability is Q1’15.

Crossbar’s Resistive RAM Technology Reaching Commercialisation Stage

While the first 3D NAND chips have just found their way to the market and most NAND manufacturers are still developing their designs, there are already a handful of next generation memory technologies in development that are slated to supersede NAND in the next decade or so. One of the most promising technologies is Resistive Random Access Memory, which is more commonly referred to as Resistive RAM or just RRAM. Similar to NAND, RRAM is non-volatile, meaning that it will retain data without power unlike regular DRAM, which needs a continuous power source. Multiple companies are developing RRAM including semiconductor giants like Samsung and SanDisk, but Crossbar, a US based startup, has probably the most advanced design so far.

I’ve been following Crossbar for quite some time, but I haven’t written anything about the company until now. The company was founded in 2010, headquarters in Santa Clara, California and has secured over $50 million in funding. The company’s roots come from the University of Michigan and its Chief Scientist and co-founder, Prof. Wei Lu, is currently an associate professor at the university. The Crossbar team consists of 40-45 members at this point, of which most have extensive backgrounds in semiconductor research and development. 

The big benefits RRAM have over NAND are performance and endurance. NAND read latencies are typically in the order of hundreds of microseconds, whereas Crossbar claims latency of as low as 50 nanoseconds for its RRAM design. Endurance in turn can be millions of program/erase cycles, although for the early designs Crossbar is aiming at more conservative ~100K cycles. 

Last week at IEDM Crossbar announced that it is now entering the commercialization stage. In other words, it has already shown a working silicon and it has also proved that the design can be transferred to commercial fab for high volume manufacturing, so the company is now working with the fabs to build final products.

At first Crossbar is aiming at the embedded market and is licensing its technology to ASIC, FPGA and SoC developers with first samples arriving in early 2015, and mass production scheduled for late 2015 or early 2016. Aside from licensing, Crossbar is also developing standalone chips with higher capacity and density, which should enter the market about a year after the embedded RRAM designs (i.e.most likely sometime in 2017).

The beauty of RRAM is that it can be manufactured using a regular CMOS process with only a few modifications. NAND and especially 3D NAND require expensive special tools (for things like high aspect ratio etching), which is why only a handful of companies are making 3D NAND. RRAM in turn can be manufactured by practically any existing fab with very little added cost, which ultimately results in lower prices due to more competition.

Additionally, RRAM doesn’t share NAND’s lithography issues. As we know, the sole reason why 3D NAND was invented is because planar NAND can’t really scale below 15nm without serious endurance and performance considerations. However, RRAM can efficiently scale to 4-5nm without any issues and in fact Crossbar has already demonstrated an 8nm chip that it built in its R&D labs (most likely using multiple patterning). Moreover, RRAM can be stacked vertically to create a 3D crosspoint array for increased density and so far Crossbar is at three layers, but first commercial standalone chips are expected to feature 16 layers and up to 1Tbit capacity. 

Obviously, there are still several hurdles to cross before RRAM is ready to challenge NAND, but it’s good to hear that there has been significant progress in development and the technology has gained interest from the fab companies. Faster, more durable and cheaper SSDs and other storage devices are a win for everyone and ultimately even 3D NAND is just an interim solution until something better comes around, which may very well be RRAM. I’ll be doing a more in-depth article about RRAM technology in the coming months as this article was more of a heads up about the state of RRAM and Crosspoint’s recent developments, so stay tuned for a deeper analysis!

Best SSDs: Holiday 2014

We published our last ‘Best SSDs’ article in July and to be completely honest the core of my recommendations has remained unchanged, but there are a couple of new entries that deserve a mention. We are admittedly a bit late with this guide since it’s less than ten days until Christmas and most people should already be done with their gift purchases, but I wanted to wait for the Samsung SSD 850 EVO launch to ensure that our guide is up-to-date going forward.

Similar to what we have done before, I will be splitting the recommendations into a few different categories specified by form factor and performance. As always, the listed prices are accurate at the time of publishing, but given the dynamic nature and regional variation of SSD pricing, it’s impossible for us to guarantee that the prices will remain accurate. Hence this article merely lists the models that you should be looking at and the final decision should be done based on the prices at that time.

Enthusiasts & Professionals: Samsung SSD 850 Pro & SanDisk Extreme Pro

My recommendations for heavy users are the same as they were five months ago. The pack is still led by Samsung’s 850 Pro, while SanDisk’s Extreme Pro is a very close competitor. Both come with a 10-year warranty and the only substantial difference between the two is that the 850 Pro supports hardware-accelerated encryption in the form of TCG Opal 2.0 and IEEE-1667 (eDrive) standards, which is a crucial feature for users who handle sensitive data (or just want to protect their data in general). 

The 850 Pro is also generally a bit faster than the Extreme Pro, so given equal pricing the 850 Pro is my number one pick. However, in 1TB-class the 850 Pro currently carries nearly $100 premium and hence I’d recommend the Extreme Pro instead as the premium isn’t justified (unless hardware encryption is a must). Amazon also has a major sale going on the SanDisk Extreme Pro right now, so as long as that’s in effect it’s a much better bargain.

Mainstream: Crucial MX100, SanDisk Ultra II & OCZ ARC 100

In July the MX100 was the king of the value market, but since then it has faced serious competition from SanDisk and OCZ. As I’ve said before, SSDs have matured to a point where any modern SSD is good enough for typical client workloads, which is why price is the dominating factor in the mainstream space. The MX100, Ultra II and ARC 100 all excel in cost efficiency and are currently available at less than 50 cents per gigabyte.

I should note that the ARC 100 doesn’t support low-power states, which reduces its power efficiency and thus the Ultra II and MX100 are better picks for laptop users as they’ll yield longer battery life. However, in terms of performance, the ARC 100 is the best out of the three thanks to the excellent performance consistency of the Barefoot 3 controller and it’s also the best fit in case you’re looking for performance on budget. 

The Ultra II in turn is slightly faster than the MX100 under very heavy workloads, but to be honest users with such workloads should be looking at the recommendations above (or right below) instead. Hence the Ultra II and MX100 are practically indistinguishable, although with the MX100 you do get hardware encryption (Opal/eDrive) in case that might come handy in the future.

Going PCIe: Samsung XP941 & G.Skill Phoenix Blade

PCIe remains as a hot topic in the industry, but it looks like we won’t see more native PCIe SSDs until mid 2015. SandForce SF3700 was supposed to be out by now and officially SandForce/Seagate hasn’t changed the schedule from Q4’14, but obviously the launch isn’t happening this year anymore. What I’ve heard is that Computex 2015 is the new release target, but I should know more about the state of SF3700 and other PCIe controllers after CES.

Given the lack of options, the Samsung XP941 is still the only worthwhile client PCIe SSD on the market. Since July we’ve also reviewed the 128GB and 256GB models, and especially the 256GB model should be alluring to many with its lower price and yet much higher performance than what SATA 6Gbps SSDs provide.

The only caveat is that the XP941 is bootable only on some Z97 and X99 equipped motherboards (RamCity has an extensive list of what motherboard models are supported and which aren’t), so users with older and unsupported motherboards are out of luck. For them my recommendation is the G.Skill Phoenix Blade, which isn’t a native PCIe drive, but despite that it did very well in our tests. Its price is a bit high, but if you really need/want more performance than what SATA 6Gbps and Intel RAID can provide, the price is justifiable.

mSATA: Crucial M500 mSATA

While the M500 is now a year and a half old and its 2.5″ version has been superseded by the M550 and MX100, the mSATA version is still alive and going strong. The core architecture in the M500 is the same as in the MX100 that we recommended above, but it utilizes Micron’s 20nm NAND instead of the newer 16nm process. Those who are familiar with SSDs and NAND are already aware that a larger lithography is actually a good thing in the world of NAND because it results in higher endurance and better performance, so even though the M500 is no longer current generation it’s still a good drive and the best value out of the currently available mSATA SSDs.

M.2 (SATA): Crucial M500 M.2

My M.2 recommendation for the SATA 6Gbps interface is the same as our mSATA, but just in M.2 2280 form factor instead if that’s what you are after. There aren’t many SATA M.2 SSDs available (though there are even fewer PCIe ones) and out of these the M500 is the only reasonably priced model. 

Generally speaking mSATA and M.2 SATA SSDs aren’t as good value as their 2.5″ counterparts are. However, if you have a laptop with an mSATA or M.2 slot and are on a lookout for an appropriate SSD, Crucial has you covered, but otherwise stick with 2.5″ drives.