The Internal Mechanism Of NAND-FLASH

• NAND-FLASH memory can be read a page at a time.
• it can be programmed in only one way - changing a bit from 1 to 0.
• Changing back to 1 can be done only in large blocks (e.g. 512KB).
• The last operation is called "erasing a block".
• This means flash is much faster in reading, then in writing
  • (because a write might require erasing the entire block, and re-programming its contents..)
• FLASH has one great limitation - each cell may be programmed up to 100,000 times (in SLC) or less (in MLC - where each cell stores 2 or more bits).
• After this - the cell deteriorates and looses its data.
• If we have a "hot-spot" location with many writes - this could be a real problem real fast.

Originally written by guy keren