Flash memory is rushing into the user life. There are many kinds of memory cards, flash memory embedded products, and Solid State Disk (SSD)/hybrid hard disk which are developed for PC/Server systems. This is because of its versatile features such as non-volatility, solid-state reliability, low power consumption, and random accessibility. Because flash memory does not have mechanical parts like a motor, it is randomly accessible without seek-delay. Seek-delay is the time to position the magnetic head to the proper position to read or write data in a hard disk, and it may take tens of milliseconds.