Differences between SLC, MLC and TLC

[fryzurra]

Hi guys,

 

I'd like to share with you some info about the flash memory and Industrial vs. Commercial SSD's.

(sorry If the english is bad, I do my best :-] )

 

All industrial grade SSD are built on SLC flash (Single Level Cell). Many many years ago flash drives were using only this technology.

Commercialization of the flash market made manufacturers to search for new technology in order to make SSD's (also CF cards, pendrives etc.) cheaper and more capacious. That's how MLC and TLC came out.

 

 

OK, so what's the main difference? Take a look below:

 

 

SLC writes 0 or 1 depending on two Voltage states, for example 0V-0,5V writes "0", 0,51V-1V writes "1".

So the possibility of making an error by writing cell with wrong bit is really low.

Now compare it with MLC where there are more Voltage states - error possibility increases dramaticly.

TLC is even more vulnerable by having eight voltage states per cell! - four bits.

Small voltage disturbance may cause mistake in cell's bit writing.

 

 

 

Another difference is the number of writes. Pls take a look at the Industrial ATP products comparing to non-industrial ATP and average consumer grade:

 

 

In this case industrial manufacturer supports its product with Wear Levelling technology.

You may read some more about it here. There are also more additional functions like:

- power protector - when the supply drops, power from PCB located capacitors allows the data from the memory buffor to be written into the flash (no data is lost, all the data is being written correctly without any errors). This function is especially helpful when there is embedded OS installed on the drive (like XP embedded or WES 7).

 

 

The industrial SSD's controller has funcion to detect the cell that runs out and prevent the data to be written on this cell.

There are always backup cells that can be switched with the used ones. In many cases manufaturer also provides software

for flash usage monitoring.

 

 

Industrial grade SLC drives may also work:

- in extended temperature environment (-40C ~ +85C),

- 24/7 (even as database drive where fast data access is required)

 

 

I hope that you will find this info helpful and that it will give you some idea why the industrial grade flash technology is so expensive.

 

[MrSuperb]

Isn't all that a tiny bit outdated?

 

Also most enterpise SSD solutions today use MLC ...

[fryzurra]

Isn't all that a tiny bit outdated?

 

Also most enterpise SSD solutions today use MLC ...

 

Mr Suberb you are right - it can be used in enterprise If there's no critical application or process depending on it.

In Industry and military projects there's SLC (extended temp. feature) 

[MrSuperb]

Mr Suberb you are right - it can be used in enterprise If there's no critical application or process depending on it.

In Industry and military projects there's SLC (extended temp. feature) 

I'd say most enterprise grade ssds nowadays use (e)MLC and similar ...

 

What do you mean by "industrial and military"?

[MrSuperb]

are you talking about embedded solutions?

[raxx]

What is the most reliable tech for ssd memory? Does anyone have a link to a good buying guide? 

[qwertywarrior]

its hard to find SLC USB drives these days :/

[qwertywarrior]

What is the most reliable tech for ssd memory? Does anyone have a link to a good buying guide? 

SLC lasts longer

but its not as big (in GB terms)

and expensive

 

looking at personal reviews

the samsung 830 is the most durable SSD drive by miles   

 

source

http://www.xtremesystems.org/forums/showthread.php?271063-SSD-Write-Endurance-25nm-Vs-34nm

[fryzurra]

I'd say most enterprise grade ssds nowadays use (e)MLC and similar ...

 

What do you mean by "industrial and military"?

 

By saying industrial and military I mean using computer system in very hostile and harsh environment, for example:

- industrial - imagine data aquisition PC working in a warehouse where there's no heating. In the winter nights temperaures drop to -25C, in the morning employee arrives and makes a "cold start" to the system. It has to work or there will be huge loses in production. So factories invest in better hardware because it's cheaper than eventual loss made of not-working system.

- military - applications that include more shock, vibration, extended temperature. Pls have in mind that when working in minus temperature when hardware passes 0C then dew-point occures which is really bad to all electronic devices. That's why you shouldn't turn on the PC immedietally after bringing it from the outside. Standard consumer grade MLC drives won't handle such conditions.

 

 

are you talking about embedded solutions?

Yes, also embedded solutions.

 

its hard to find SLC USB drives these days :/

Yes but in b2b relations they are available.

http://ap.apacer.com/business/industrial-ssd