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.
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Beenthere - Thursday, February 23, 2012 - link
While the transition from SLC to MLC and now TLC sounds good, the reality is SSD makers have yet to resolved all reliability or compatibility issues with MLC consumer grade SSDs.Last time I checked OCZ was on firmware version (15) and people are still experiencing issues. The issues are with all SSD suppliers including Intel, Smasung, Corsair, etc. not just OCZ.
If data security is important it would be wise to heed Anand's advice to WAIT 6-12 months to see if the SSD makers resolve the BUGS.
extide - Thursday, February 23, 2012 - link
Go with an Intel, Samsung, or Crucial drive. They are reliable and fast.Beenthere - Thursday, February 23, 2012 - link
Actually no one has any lock on SSD reliability. Intel, Samsung and Crucial have ALL had issues that required firmware updates to fix BUGS. We don't know how many more BUGS exist in their or other brands of consumer grade SSDs.Not all HDD drives have issues. Yes some do especially the low quality high-capacity SATA drives. That however is not a good reason to buy a defective SSD.
SSD makers are just cashing in on gullible consumers. If people will pay top dollar for defective goods, that's what unscrupulous companies will ship. If consumers refuse to accept CRAP products, then the makers will fix the products or go broke.
ckryan - Thursday, February 23, 2012 - link
Yes, because everyone knows HDDs are infallible, never die, and are very fast...Oh wait, none of that is true.
MonkeyPaw - Thursday, February 23, 2012 - link
As someone who tried to use a Sandisk controlled SSD recently, it's not as obnoxiously simple as you make it sound. It's one thing to know a drive will fail, it's another to experience BSODs every 20 minutes.Making proper backups is the solution to drive failure, but a PC that crashes with regularity is utterly useless. I don't hate SSDs, I just want more assurance that they can be as stable as they are fast.
martyrant - Thursday, February 23, 2012 - link
So I've had the Intel 80GB X-25M G2s since launch with zero issues, no reason to upgrade firmware, no BSODs or issues. I recently bought one of their 310 80GB SSDs for an HTPC--again, 5 months later, no issues, no problems, no firmware updates.I've had a friend who's had two Vertex 2's in RAID 0 since launch with zero issues.
I also have a friend who has had a Vertex 2 drive die 4 times on him in under 2 months (this is more recent).
As of late, it seems that a lot of manufacturers are having issues but most I believe are the latest SandForce controllers which are causing the issues.
This is why you see people who use their own controllers, or one other than a recent SF controller, not having issues.
I feel bad, I really do, for those people who have been screwed over recently by the SSDs that have been failing--but I mean generally doing the research before hand benefits you down the road in the long run.
The reason Crucial, Intel, and Samsung SSDs are not having issues is because Crucial uses a Marvell controller, Intel uses its own controller, and Samsung uses it's own controller as well. This may not be true for all their drives, but most of their drives (the reliable ones) are of those controller types.
Just do your research before hand and don't be an SSD hater because they really are, when you shell out the cash to not get the cheapest thing on the market, the biggest upgrade you can do to your computer in the last 3-5 years. I haven't upgraded my mobo/cpu in either of my 3 computers in years but you bet I bought SSDs.
Holly - Saturday, February 25, 2012 - link
My OCZ Vertex 3 serves without glitch since 2.13 firmware was released. Before that occasional system freezing was major pain. Otoh I don't feel like updating to 2.15 firmware, rather being happy with what's working now :-)jwcalla - Thursday, February 23, 2012 - link
Yeah but even HDDs have major reliability problems... especially the high-capacity consumer drives.psuedonymous - Thursday, February 23, 2012 - link
There have been a few products already mixing an SSD with a HDD to allow oft-used data to be quickly read and written while rarely used bulk data that get's streamed (rather than random access) e.g. video is relegated to the HDD. Why not do the same with two grades of NAND? A few GB of SLC (or MLC) for OS files and frequently accessed and rewritten program files, and several hundred GB of TCL (or QLC, etc) for less frequently written data that it is still desirable to access quickly (e.g. game textures & FMVs). Faster than a HDD hybrid, cheaper than an all-SLC/MLC design, and just as fast in the vast majority of consumer use cases (exceptions including non-linear video editing, large-array data processing).kensiko - Thursday, February 23, 2012 - link
Yes that's what I thought reading this article.We just have to make the majority of writes on MLC and put the static data on TLC. Pretty simple and probably feasible in a 2.5in casing.