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3 bit-per-cell flash coming soon

I'm in Silicon Valley at the Flash Memory Summit. The big news: 8 GB, 3 bit-per-cell (3bpc) NAND flash. What does it mean to you?
Written by Robin Harris, Contributor on

OK, I'm in Silicon Valley at the Flash Memory Summit, a conference aimed at industry insiders. The big news so far: Intel and Micron announced they are sampling an 8 GB, 3 bit-per-cell (3bpc) NAND flash.

Sampling means that they are building a few on a proto line for big potential customers. Commercial availability is expected in Q4, but don't be surprised if that date slips.

Not too scary What does 3bpc mean to you? Basically, 50% more capacity per $. That's good. The sounds-scary-but-not-really downside: it will only handle about 1,000 writes before failing.

Why isn't that as scary as it sounds? Reason 1: this flash will 1st go into products like USB thumb drives or SD cards, where you won't write to it 1,000 times anyway.

Reason 2: due to wear-leveling - a process that spreads writes across all capacity - you'll have to write 8,000,000 MB of data to an 8 GB part before it croaks. That is 2 million 4 MB JPEGs. That's a lot of snapshots.

Since most of these will go into devices that hold 16, 32 or even 64 GB of flash, multiply 2 million by 2, 4 or 8 and it is obvious that casual users will never wear out 3bpc flash.

Write performance will suffer as well, but how much remains to be seen. The effect on you will depend on how many flash chips are on the device: flash controllers write data in parallel, so the more chips the faster the write.

The Storage Bits take 3bpc products will have a ripple effect on other flash parts. Price sensitive products - most flash parts - will want to move to 3bpc ASAP, but the volumes won't be there. But as production ramps, 2bpc flash will face big price pressure as vendors with older fabs try to keep them running.

Translation: expect that flash prices will resume their downward path after 3 quarters of flat prices. Yay!

Comments welcome, of course. SSD vendors shipped about 10 million SSDs in the last 12 months. Sounds good, but tiny compared to over 500 million hard drives.

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