Western Digital touts tiny flash card with massive write cycles for video surveillance

Western Digital has unveiled a microSD format flash card for video cameras that can sustain 3,000 write cycles and pump out data at 30MB/sec.

WD said the WD Purple QD312 is also suited for intelligent edge devices that need access to large amounts of data.

The QD312 is the first product in the Purple range that is not a hard disk drive (for instance, this 12TB model). Think large fingernail size, containing 256GB at best – a fraction of disk drive’s capacity.

But unlike the bulky disk drive, MicroSD storage can be loaded into the video camera to increase in-cam storage.

WD has launched three WD Purple SC QD versions:

  • QD102 with 32GB and 64GB capacities, supporting speed class 10 (see note 1 below) and 32 or 64TBW (terabytes written)
  • QD102 with 128GB and 256GB capacities, UHS speed class 3 (U3) and up to 256TBW
  • QD312 with 64GBm, 128GB and 256GB capacities, running at Speed Class 10 with up to 768TBW

All three use 3D NAND. The 768TBW indicates 768,000/256 = 3,000 full write cycles for the 256GB capacity. A 3,000 flash write cycle is quite high for microSD cards, and WD cites this to justify the extreme endurance tag. However, the warranty period is just two years. SSDs generally come with a five-year warranties and can have a 10 drive writes per day rating.

A WD Ultrastar DC SS530 SSD has such a rating and that means 3,650 full write cycles. So the QD312 is not such an extreme endurance product, after all.

The card is water-proof, shock-proof, impact proof, X-ray proof, and magnet proof and operating temperature is -25°C to 85°C, according to WD. Memory management, power immunity, auto/manual refresh, ECC, and wear-levelling is managed through the firmware.

Also, customers with compatible cameras, get notified when it is time to service the Purple microSD card.

A table of SC QD102 drive specs

WD provides a separate and different table incorporating the SC QD312 and we’ve reproduced that here:

SC QD102 and QDF312 specs

It is currently sampling its Purple SC QD312 Extreme Endurance microSD card to OEMs. Get a datasheet here.

Note 1. Class 10 speed is 10MB/sec, while U3 is 30MB/sec.

Note2. MicroSD cards, at 15 mm × 11 mm × 1 mm, are slightly larger than UFS format cards, which are intended for video cam use, and also slower. A Samsung eUFS card can operate at up to 1,000/260 MB/sec when sequentially reading/writing.

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