The Register®

Original URL: http://www.theregister.co.uk/2012/07/11/smart_tlc/

The Great TLC flash cash-slash: Coming soon to tablets, Ultrabooks

Super-dense storage tech moves towards 20K cycles

By Chris Mellor

Posted in Storage, 11th July 2012 19:13 GMT

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SMART recently announced that its controller technology, the Guardian Technology Platform, could get MLC flash to do 50 full drive writes/day for five years [1]. Now SMART's president has said 1Xnm TLC could be driven to 15,000 to 20,000 PE cycles using SMART's Guardian controller technology, representing a 30X - 40X increase – implying 10-11 FULL DRIVE WRITES a day for five years...

That means 1Xnm TLC could be usable in some enterprise storage scenarios and should be a candidate for tablet computing storage. Ditto 2Xnm TLC. We'll remind ourselves here that Apple bought the Anobit [2] flash controller firm for its MLC and TLC endurance extending technology. Seagate bought DensBits [3] for the same TLC reason.

SMART's president John Scaramuzzo told El Reg: "The Guardian Technology Platform can deliver an SSD that achieves exponentially greater endurance than off-the-shelf TLC Flash. At the 1x process node, TLC with raw endurance of 500 PE cycles can potentially be extended up to 15K-20K PE cycles."

So how did we get to that 10-11 drive writes a day figure? Well, 20,000 divided by five gives you 4,000 a year. That number divided by 365.3 (days in the year) gives you 10.95. We'll round that down to 10-11 PE cycles a day, implying 10 drive writes a day for five years. Not bad, not bad at all.

Here's the background: 3-bit flash, Three Level Cell (TLC) flash has a much shorter endurance because cells can be written to in a program erase (PE) cycle far fewer times than 2-bit multi-level cell (MLC) flash which has a shoer endurance than 1-bit (Single Level Cell or SLC) flash. Each step down in cell size, described by the process geometry size in nanometres, reduces endurance some more.

Thus a 3Xnm TLC cell – meaning 39-30nm process geometry – could do 1,250 PE cycles; a 2Xnm cell (29-20nm) could do 750; and a 1X cell could do 500 (AnandTech numbers [4]).

A flash drive controller can increase endurance through having spare cells on hand to replace worn-out ones; over-provisioning by detecting and correcting errors in the read signal from cells that are wearing out; via ECC; by better interpretation of the read signals; digital signal processing; as well as other techniques.

El Reg's conclusion: TLC flash prospects for tablet and enterprise use are real. Product is coming. ®

Don't forget to post your comments here [5], please.