Understanding TLC NAND
by Kristian Vättö on February 23, 2012 1:14 PM EST- Posted in
- Storage
- SSDs
- OCZ
- Indilinx Everest
- TLC
Availability and Controller support
Just to make this clear, TLC isn't anything new. For example Hynix had a 32Gb 48nm TLC die in 2008. This is because TLC was originally used for devices like USB flash drives, where its poor endurance would be negligible. Most SSD OEMs have been toying with TLC SSDs for at least a year now but we haven't seen any commercial products. OCZ had originally planned to introduce its first TLC based SSD in the Q1 2012, however TLC pricing simply hasn't made sense yet. Unless OCZ can leverage a significant cost savings over 2-bit-per-cell MLC, the added headaches of bringing a lower performing TLC part to market don't make sense.
However there's still significant motivation to migrate towards TLC NAND. Further bringing down costs, particularly for consumer SSDs aimed at light, particularly read heavy workloads makes a lot of sense. Increasing pressure from Intel to deliver cheaper SSD enabled Ultrabooks, and Apple's desire to move all mainstream Macs to solid state storage are two major motivations. MLC NAND pricing will eventually get low enough to meet these (and more) needs, but TLC definitely accelerates the process.
TLC does require controller and firmware support. In the client SSD space only OCZ has been aggressive with announcing that its Indilinx Everest controller supports 3-bit-per-cell NAND.
Adding controller support for an extra bit per cell is more than just updating the datasheet and claiming it works. The ECC engine needs to be updated as the controller will face more frequent and more severe errors with TLC NAND (and its associated lower endurance rating).
Maintaining low write amplification is even more important with TLC NAND. With significantly fewer available program/erase cycles, burning through them due to high write amplification isn't acceptible. While NAND endurance isn't really an issue for most client MLC drives, it may be an issue for TLC based drives.
Facebook
Twitter
RSS
90 Comments
View All Comments
BPB - Thursday, February 23, 2012 - link
I just ordered the OCZ Synapse to use as a caching drive. The reviews all rave about speed increases. I am putting it in my main system. Would be nice if you could tell us where they fit in.Also, anybody got recommendations on an SSD to get an older system to feel faster for surfing and the like?
Kristian Vättö - Thursday, February 23, 2012 - link
It's hard for me to say anything about caching SSDs because we haven't reviewed any other than Intel 311 Series (yet). IIRC Synapse comes with its own caching software which is different from Intel's SRT.Fortunately, we have some more staff working on SSD stuff now. As you may have noticed, so far Anand has done all the SSD reviews. To reduce Anand's workload, I'll be doing some of the SSD reviews in the future, which should allow us to review more SSDs. In fact, I have Plextor M3 SSD on its way here :-)
As for the SSD for an older system, is it a desktop or laptop? I think the best option would be a SSD+HD combo because that is cheap and still lets you have a decent amount of storage. You can try to find older SATA 3Gb/s SSDs (e.g. Intel X25-M G2 or Samsung 470 Series, they are very reliable). You can even hunt for a used drive, some people are already switching for faster SATA 6Gb/s SSDs so you may find a bargain.
ckryan - Thursday, February 23, 2012 - link
Synapse comes with NVELO's dataplex caching software, and there should be more consumer target caching solutions out soon.macuser2134 - Friday, February 24, 2012 - link
An upcoming Plextor M3 review - this is exciting! It will certainly be interesting to find out how a Plextor drive compares to other manufacturers.As a side note the "Pro" version of the Plextor M3 just started selling on Newegg only 2 days ago. Models PX-128M3P, PX-256M3P etc.
seanleeforever - Monday, February 27, 2012 - link
there is something else the articles did not address. the life time of a certain SSD device is a combination of its cell reliability and how often it get re-written to.take a look at the second page, it may look like at 3x nm, the SLC can last 20 times more than MLC. However, from a device point of view, a 120 GB SLC can well last 40 or more time than a 120 GB MLC because as you write and delete file over and over.
for example, in order to re-write the entire 120 GB of information, each cell of the SLC only get erase-write once while a 120GB MLC will most likely been erased-write twice (say to change 11 to 10 to and to 00 , a SLC will need to erase and write once on each of two cells where MLC will need to erase and write at least 3 times on a single cell), or try to imagine a super MLC cell that has all the voltage level needed for 120GB storage in one cell, then every-time something is changed that cell get re-written.
this just get a lot worse in TLC design, as you reduce the number of cells to realize more storage space, you are reducing the error margin as well as increasing the cycles. the old saying still applies "there is no displacement for replacement". there is no free lunch.
BPB - Friday, February 24, 2012 - link
Thanks for the reply. I'll look into your suggestions, though given what I understand to be the limited life of SSDs I think I'll go new. Thanks again.Shadowmaster625 - Friday, February 24, 2012 - link
Please keep an eye out for caching solutions such as NVELO's dataplex caching software. I am looking for one that works with XP. It doesnt make much sense to have to upgrade the OS if all you're looking for is a cheap upgrade to a 5 year old pc. $69 for a caching drive is one thing. $220 for a drive and an OS is quite another...JNo - Friday, February 24, 2012 - link
Agree. I mentioned the NVELO caching software on these boards weeks (maybe months) ago after storagereview looked at them. It would be really good if you got some of their drives or even just software in to review. It is exciting that there is a competitor to Intel's caching in this space. Who knows? They may even be faster, cheaper and better....xrror - Monday, February 27, 2012 - link
I'd also like to see some analysis on NVELO "solutions." I was looking pretty seriously at buying Corsair's version of this with their Accelerator series drives as an "impulse purchase" but lack of availability of their 60Gb package and a good read of NVELO's software "licensing" put a quick halt on that.NVELO looks like a killer app assuming it works. Sadly I expect that it does live up to it's claims, but their DRM is pretty harsh. It's locked to your hardware, so if you say change your video card you must "re-activate."
I know that for most people that's no worse than windows itself, but I change hardware a lot, and/or I'd like to be able to move the SSD cache to other machines in my house w/o worrying that I'll get DRM lockout.
Roland00Address - Thursday, February 23, 2012 - link
57 months ago (4.75 years) you could get a 16gb supertalent for 600 dollars41 months ago (3.41 years) you could get a 80gb intel (1st gen) ssd for 600 dollars.
Small deviations make a big difference when you are calculating exponential growth (and decrease)