How Does Flash Storage Work?
Most NAND flash memory on the market today stores one, two, or three bits of data per cell. Such types of flash are respectively called Single-Level Cell (SLC), Multi-Level Cell (MLC), and Triple-Level Cell (TLC). Of these, SLC has the best data retention, endurance, and reliability, as well as the highest cost, followed by MLC and TLC.
SLC is considered to be the most fault-tolerant. This is because while an MLC cell holds two bits of data (00, 01, 10, or 11), an SLC cell holds just one bit (0 or 1). The chance of data error is minimized when each cell represents just one bit of data. However, to store the same amount of data on SLC NAND requires a lot more cells than with, say, MLC. This, plus the higher cost per bit of an SLC device, discourages many enterprises from choosing SLC.
Endurance and how it is rated
The lifespan of NAND flash is measured by number of P/E cycles, meaning the amount of Program/Erase operations the flash memory can perform before its oxide layers degrade to such a point that it can no longer hold the requisite amount of electrons required to represent data reliably. The P/E cycles for SLC products range from 50,000 to 1,000,000; for MLC, 3,000; and for TLC, around 1,000.*
*Note: P/E cycles vary by NAND flash type, testing environment, and manufacturing process node.
Going from planar to 3D layering
As die processing continues to advance, die size shrinks. The result is that 2D planar NAND memory is reaching density limitations. As such, manufacturers have begun looking to 3D vertical stacking for a breakthrough. This change comes with its own set of issues, such as data retention, drive reliability, and overall performance. Fortunately, by utilizing advanced flash management techniques such as firmware coding and programming, manufacturers are able to address these issues and unleash new capabilities and high performance, all while ensuring that flash products remain affordable.
Transcend’s latest 3D NAND SSDs, for instance, come bundled with many of Transcend’s advanced technologies for greater performance and reliability. SLC caching and a RAID engine power-up read and write speeds and extend product life; a RAID engine also protects data and enhances drive stability; and LDPC (Low Density Parity Check) Error Correction Code detects and corrects bit errors. These features are all crucial for memory products being used in AIoT applications.
Cutting-edge 96-layer 3D NAND solutions
Transcend has begun implementing industry-leading 3D NAND technology that allows 96 layers of NAND flash chips to be vertically stacked in a 3-bits-per-cell architecture. This density breakthrough not only significantly improves storage efficiency over its 64-layer predecessor, it also boasts high endurance. Transcend further employs an internal testing tool to ensure the endurance of its 3D NAND flash. Each 96-layer NAND flash chip in SSDs and memory cards can process an average of 3,000 P/E cycles.
Where cost-effectiveness meets reliability
Products featuring 3D NAND cells are cost-effective solutions that offer performance and reliability at an affordable price. Transcend's use of 96-layer 3D NAND technology greatly boosts speed, endurance, and reliability. Its SSDs feature data retention equivalent to that of multi-level planar NAND flash, but at a much lower cost per bit. As such, these SSDs integrate the advantages of high performance and exceptional endurance under intensive read/write cycles, making them ideal for industrial and enterprise use.