Sign in with
Sign up | Sign in
Your question

SDXC cards should have already reached 1TB if not 2TB.

Tags:
  • SecureDigital
  • Flash Media
  • SD Card
  • Storage
  • SDXC
Last response: in Storage
Share
May 24, 2014 10:49:32 PM

It is well known among digital photographers that the highest capacity SD cards are 256GB and produced by Lexar. Lexar has been making them since the winter of 2012 with 0 competition. Yet, in the intervening 15 months, no other company had anything to compete with Lexar, with the Lexar cards maintaining their high price of around $400. Google searches would only turn up Lexar's product, reviews about its product, or rumors of higher capacity cards in the making from the likes of SanDisk or Kingston.

It was only a month ago that PNY began selling a competitively-performing 256GB card for only a quarter of the price ($99 on TigerDirect.com after rebate). In fact, it's so new that PNY's own website does not yet acknowledge its existence! A search for other companies who sell (or are planning to sell) 256GB cards now turns up some relatively unknown players in the SD card market:

  • Duracell: 256GB cards are coming soon, but their 64GB cards are priced at an incredible high of $349.99 for performance that is worse than mid-range offerings from its competitors (though other sites sell for a more reasonable double-digit price). It says right on their site that their cards' read/write speed is 60MBps/35MBps. I guess it's no surprise why Duracell is still only known for selling batteries.
  • Kingmax: 256GB cards are also coming soon, but they are a relatively unknown company. While they have products listed on Newegg and Amazon.com, most of their items have 0 reviews/ratings with a few having 1 or 2 ratings.
  • Green House: a Japanese company with little global presence. It currently sells 256GB SDXC cards for about $500. And apparently, this has been announced since November 2013 but hidden away from the prying eyes of Googlebot. (But Tom's Hardware, apparently, had a short article about it last year.)
  • Panasonic: ???
Notice that no popular SD card manufacturer has even hinted at developing 256GB SD cards. Toshiba, which manufactures its own NAND, and Sandisk, its close partner, still sells only 64GB and 128GB cards respectively. Samsung recently refreshed its product offerings with the largest capacity SD card still being 64GB. To estimate what should be possible now, consider the fact that SanDisk recently released a 128GB MicroSDXC card. A regular-sized SD card is about 9 times the volume of a MicroSD card (over twice the thickness, twice as wide, and twice as long), and if it were hollow it could comfortably fit 8 MicroSD cards inside of its shell. That means that SDXC cards should be capable of holding over 1TB! Furthermore, the SD family of cards all contain a microprocessor and NAND chip. If in a volume containing 8 of them, 7 microprocessors were replaced with NAND chips, then we'd be knocking on the door of 2TB territory. 2TB SDXC cards should already be possible.

What's holding these manufacturers back? 4K video, and soon 8K video, recording will become the norm soon with ever-increasing resolution of DSLRs.

More about : sdxc cards reached 1tb 2tb

a c 92 G Storage
May 25, 2014 12:38:19 PM

What's holding the manufacturers back is a lack of reliable high-density NAND Flash memory and the constraints of the SDXC formfactor. The highest density technology is Samsung's TLC-NAND which stores 3 bits per memory cell but the write endurance is only a few thousand cycles at best. This is not the kind of technology that a manufacturer that sells high-quality products wants to go near.

The SD and SDHC specifications only allow up to 32 GB of capacity. It may be logically possible to go beyond this, but it's a breach of specification to do so, which will make many manufacturers reluctant. The SDXC specification allows for capacities up to 2TB, but this doesn't mean that devices of this capacity can be manufactured at this time.

The only company in that list that actually produces the NAND Flash that is used in its own products is Lexar, and that's because they're owned by Micron. They produce MLC NAND up to 1 terabit, but it only comes in an LBGA formfactor that's fine to use for SSDs but too big to use for memory cards. They would need to arrange 8 of them to reach a 1 terabyte capacity. Instead, they probably use 8 of their 256 gigabit chips which have a more compact footprint and are suitable for configuration within the SDXC formfactors.

Furthermore, reading and writing 4K video requires massive amounts of device bandwidth that is only achievable through reasonably powerful storage controllers. Reducing the number of storage controllers or complexity of the storage controller may make room for additional memory, but may also reduce the device's IO capabilities below an acceptable threshold.
!