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NAND Flash Storage interface

For the installed flash modules, I have been wondering if flash management (garbage collection, wear leveling, etc.) is managed via a flash controller, or is managed by the iOS. Integrated flash/controller modules are often easier to implement within an OS, rather than trying to do flash management in the OS (which requires a pre-defined command set through the interface).

Anyone know?


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I believe that it is managed on the flash controller, or the lowest level of the startup chain (the bootrom "iBoot") iOS doesn't interface with the flash at that low of a level. The kernal sees the flash as two HFS Partitions (Mainly because iOS's core structure is built from OS X) There are also no kernel extensions in iOS for that level of interface either.

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Why two HFS partitions (versus one)? Your answer makes perfect sense, but wondered if there was any device ID characteristics that caused loading of special commands (drivers) to communicate across the interface (which seems to be eMMC, or hybrid of such).

Indeed the best logic for flash management should be in the incorporated flash controller (easier to keep pace with lower level hardware changes than in the OS).



One is used for storing iOS, it's about 1.5GB (On iPad) in size (It makes up the "Other" that you see when the device is connected to iTunes") it is mounted at "/" and is "Read Only" (Unless the device is jailbroken) The 2nd partition is used for Apps, Music, Movies, ect, and it mounted at "/var" (This is what iTunes has access to) and it occupies the rest of the devices space. All iOS devices behave like this.


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