<p>The  explosion of flash memory technology has dramatically increased storage  capacity and decreased the cost of non-volatile semiconductor memory.  The technology has fueled the proliferation of USB flash drives and is  now poised to replace magnetic hard disks in some applications. A solid  state drive (SSD) is a non-volatile memory system that emulates a  magnetic hard disk drive (HDD). SSDs do not contain any moving parts,  however, and depend on flash memory chips to store data.<br /> <img src=\"images/Third_Generation_Solid_State_Drives_.jpg\" alt=\"\" />With  proper design, an SSD is able to provide high data transfer rates, low  access time, improved tolerance to shock and vibration, and reduced  power consumption. For some applications, the improved performance and  durability outweigh the higher cost of an SSD relative to an HDD.</p>
<p>Using  flash memory as a hard disk replacement is not without challenges. The  nano-scale of the memory cell is pushing the limits of semiconductor  physics. Extremely thin insulating glass layers are necessary for proper  operation of the memory cells. These layers are subjected to stressful  temperatures and voltages, and their insulating properties deteriorate  over time. Quite simply, flash memory can wear out. Fortunately, the  wear-out physics are well understood and data management strategies are  used to compensate for the limited lifetime of flash memory.</p>