Nearly two years ago Micron announced its first native PCIe SSD: the P320h. We finally got to review it over a year later. In the time between announcement and availability however, the market had changed considerably. The P320h still used expensive 34nm SLC NAND, while much of the enterprise PCIe market moved to MLC/eMLC/MLC-HET based solutions to deliver better cost per GB. Today, Micron fills the hole in their product stack with a PCIe SSD that uses 25nm MLC NAND: the P420m. The P420m is built on the very same controller as the P320h, with nearly identical firmware (save for changes to support the new NAND type). We're still looking at a 32-NAND-channel PCIe x8 controller, it's just hooked up to a different type of...