MLC vs. TLC

[Snipe343]

What is the difference between the two?

I know they're multi level cell, and triple level cell. But I'm having a hard time finding/understanding what these mean in use.

Also I've read that TLC doesn't last as long? Is that true and if so by how much in comparison to MLC?

Thanks for any help!

 

[Fourstaff]

Long story short: its all to do with packaging the bits, we have SLC which is one bit to TLC which is 3 bit. TLC comes with the shortest endurance, but you will still need to hammer the drive very hard to make the difference show. Imo only servers need to pay attention, for consumers your computer is more likely to be obsoleted long before the drives reach their expected death time.

Something interesting: http://techreport.com/review/25320/the-ssd-endurance-experiment-22tb-update

 

[BiggieShady]

You would need to write around 40 TB of data for TLC cells to start failing ... they did 22 TB so far

 

[Fourstaff]

You would need to write around 40 TB of data for TLC cells to start failing ... they did 22 TB so far

I hammered a grand total of 1.25TB over 3 months, and that is indiscriminately downloading videos and games with no regard to endurance. At this rate I will need 8 years to kill my drive, which is about time I should upgrade my SSD. Endurance is a non issue I would say.

 

[Sasqui]

Here's an article that's spot on to your question:

http://www.anandtech.com/show/5067/understanding-tlc-nand

MLC has two bits per cell and TLC has 3 bit per cell. With each added bit, there's a lot of complexity added to control each cell. Here: http://www.anandtech.com/show/5067/understanding-tlc-nand/2

Example of the problem:

Here comes the differerence between SLC, MLC and TLC. The fewer bits you have per cell, the more voltage room you have. In other words, SLC can tolerate more changes in the voltage states because it has only two states. In TLC, there are eight, so the margin for errors is a lot smaller.

 

[qubit]

I hammered a grand total of 1.25TB over 3 months, and that is indiscriminately downloading videos and games with no regard to endurance. At this rate I will need 8 years to kill my drive, which is about time I should upgrade my SSD. Endurance is a non issue I would say.

Indeed, just think of all those hords of users ranting on forums everywhere about their SSDs dying prematurely! There aren't any.

This was something that I was worried about a while back, but the evidence says otherwise. I haven't bought one yet, because they're still a bit pricey for one of those nice 256GB Samsung 840 Pro ones and I keep spending money on other bits for my PC. Just blew £400 on two graphics cards and a sound card.

 

[EarthDog]

There are a ton complaining about it... but they are not dieing because of bad NAND, it is controller related.

 

[qubit]

There are a ton complaining about it... but they are not dieing because of bad NAND, it is controller related.

It's surprising to see the controller dieing. I take it this affects the cheaper brands more?

 

[EarthDog]

OCZ had a lot of problems with drive death, and it wasnt because of the NAND wearing out. Most drive failures are not because of NAND wearing out. For YEARS people were saying, but nothing ever proved until lately, that you need to write 10GB /day for XX years before NAND would die.

 

[FX-GMC]

You would need to write around 40 TB of data for TLC cells to start failing ... they did 22 TB so far

Over at xtremesystems, one guys Samsung 840 made it to 430TB before the drive failed.

http://www.xtremesystems.org/forums/showthread.php?271063-SSD-Write-Endurance-25nm-Vs-34nm&p=5163560&viewfull=1#post5163560

And up to 100TB at tweaktown

http://www.tweaktown.com/articles/5196/samsung-840-ssd-storage-endurance-testing-tlc-to-the-end/index3.html

 

[TheOne]

OCZ had a lot of problems with drive death, and it wasnt because of the NAND wearing out. Most drive failures are not because of NAND wearing out. For YEARS people were saying, but nothing ever proved until lately, that you need to write 10GB /day for XX years before NAND would die.

Yea, most SSD related issues stem from the firmware, TLC NAND is just slower and has a shorter life expectancy, which is supposed to be the trade off for more cost effective NAND for the consumer market.