In this example, we've shown the math behind how a 480GB or 512GB SSD might be created. Let's look deeper:Įach Flash module can contain multiple flash dies. There are two bits of data per cell in this type of NAND, as opposed to single-bit storage on SLC and triple-bit storage on TLC. “MLC” represents the NAND Type – multi-level cell, in this case. The nm number is the process node for the silicon, as cut at the fabrication plant and supplied to SSD makers for use in their drives.
The controller handles wear-leveling, garbage collection, extending P/E cycles, and governs Write Amplification Factor (WAF), all of which we've discussed in this previous content.įocusing on the NAND, we might imagine that our sample SSD above uses 16nm MLC Flash NAND. In this imaginary SSD, we have completely maxed-out our controller's available channels with flash modules. Our simplified SSD above is comprised of a controller – effectively the SSD's CPU, as it is more-or-less a small computer, eight channels, and eight flash modules that are connected to those channels. Here's a simplified SSD image we made for the 2014 article: Each piece of data is transacted as a bit, and is stored at the 'cell' level within the SSD.
NAND does not magnetically store its data instead, NAND Flash takes the route of electrical read/write operations by checking voltage states.
There is a mechanical component to hard drives which governs their maximum operating speed – tied to the speed of the moving head (like a record player) – and increases noise/vibration with increases to maximum throughput. A hard drive, though, uses electromagnets and large, spinning platters with physically moving headers for data storage. In this regard, NAND Flash on SSDs serves a similar purpose as the platters of a hard drive: It stores data with relative permanence, as opposed to volatile system memory which only temporarily stores data for recall. NAND Flash is a non-volatile, permanent memory.
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