SanDisk 400GB MicroSD Card – QLC in Action?

SanDisk 400GB MicroSD Card – QLC in Action?

Chris EvansStorage

Yesterday SanDisk/Western Digital announced the availability of a 400GB microSD card, doubling the capacity of their previous offering.  In a press release WD said:

Western Digital achieved this capacity breakthrough by leveraging its proprietary memory technology and design and production processes that allow for more bits per die.

Is this the first, or at least one of the first examples of QLC NAND technology in the wild?

SanDisk Ultra<sup>®</sup> <i class="no-caps">microSD</i> UHS-I Card

The product page for the 400GB* SanDisk Ultra® microSDXC™ UHS-I card doesn’t provide any specifics on the memory technology used and neither does the press release, however based on what we know about Toshiba/WD’s BiCS3 technology (link), QLC should be producing 96GB per die.  Cram four of these into a microSD card and you have 400GB, or thereabouts.  As this is a consumer device, we wouldn’t expect any over provisioning, so the maths just about works, when using decimal GB.

At a recommended $249.99, the 400GB card isn’t cheap.  Pricing of course isn’t based on the cost of producing the NAND, but on the premium the consumer will pay for such a large capacity in a single card.  Producing capacity for the consumer market first also makes sense, as it provides the ramp up for manufacturing and quality testing.

The Architect’s View

For the last few years I’ve been giving training presentations on storage and used the highest capacity microSD card as an example of where the industry has reached in terms of scalability.  Five years ago I quoted 32GB microSD devices and in that time we’ve seen around a doubling of capacity every two years.  This capability is exceeding that achieved by the HDD manufacturers (around 30% CAGR) and it’s not a surprise that flash drive capacity is overtaking that of HDDs.  The more interesting question is when will the cost ratio be low enough to consign HDDs to all but the most mundane archive and cold storage use cases.  I think the answer is not that long.  All we need is a crash in the price of NAND and we will be there.  Could we imagine the death of the hard drive by 2020?

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