Over the past decade, consumer electronic devices have gone through massive changes in terms of storage. Storage now includes SSDs & Flash and yet the symbol for storage remains the Floppy Disk. Lately, 3D storages are also being talked about. Ganesh Guruswamy, Senior VP, Flash Product Group & Vivek Tyagi, Director for Business Development in India, SanDisk brand Commercial sales and Support, Western Digital Corporation, talked with Saurabh Durgapal of EFY on the advancing storage devices around us.
Q: What would you describe as bottlenecks for advancing storage devices?
A. Any kind of storage will be accessed via a data transfer protocol. There are certain restrictions in every protocol, limiting storage access. If you want faster storage access then we move from Universal Series Bus (USB) 3.0 to Serial Advanced Technology Attachment (SATA) or PCIe (Peripheral Component Interconnect express). The industry is also simultaneously shifting from 2D to 3D storages.
Q: How significantly are access speeds limited by interfaces?
A. A piece of flash memory can be inserted in both a solid-state drive (SSD) and a USB drive. The USB protocol is limited by industry regulations such as USB 2.0 or USB 3.0. For faster access speeds, protocols like SATA (Serial Advanced Technology Attachment) or Peripheral Component Interconnect express (PCIe) are the most commonly used. Once you have an estimate on the access speed of your application, you can choose the suitable protocol.
Q: How has flash memory scaled in the past few years?
A. As we are seeing Moore’s law, is out the window now. We scaled down from 180 nm to 130nm to 90 nm to 65nm which allowed costs to scale down proportionately. Similarly, for NAND technology, we scaled down from 32nm to 24nm to 19nm and we are now at 15nm.
Q: How significantly is ReRAM different over flash?
A. Resistive Random Access Memory (ReRAM) is different from the flash memory, wherein we employed Complementary metal–oxide–semiconductor (CMOS) transistors. The materials used in resistive memories for the formation of a cell are very different from flash. These are resistive in nature, so we work with that property of the material to store data.
Q: What lead to the move towards 3D technologies?
A. In CMOS, we have the n-junction and the p-junction and manipulation is done by means of electrons. We are now storing few electrons in a cell, and with those we are differentiating between a “1” or a “0”. But at those levels, we have limited control over those individual electrons, hence the reason to look further into atoms.
Q: Where do 3D storages stand today?
A. 3D X point and ReRAM come under a different class of storage memories. Let’s consider flash and Dynamic Random Access Memory (DRAM) as memory options. DRAM is very fast, but we can’t put a lot of it due to the cost and space involved. On the other hand, we can use a lot of flash, but it is not as fast. So, we need something that provides us with best features of both worlds. This is where storage class memories come in, to provide performance close to DRAM and be faster than flash.
Q: Could we look at a future with storage class memories as main storage options?
A. Storage class memories could very well replace the other memories but at a certain price point.