What is wear leveling in SD cards? How I can check my sd card has wear leveling or not?
This is from SanDisk's website:


  Wear Leveling
  
  Wear Leveling ensures even distribution of erase operations on all
  blocks within the NAND flash. That is, each block within the NAND
  flash is erased and written approximately the same number of times as
  every other block within the drive.
  
  To understand Wear Leveling, one needs to understand the different
  addressing schemes in a system. The operating system (OS) uses Logical
  Block Addressing (LBA) to read and write a block of data from the
  drive; the flash controller uses physical addresses on the flash to
  read and write data.
  
  Wear Leveling is based upon two mechanisms:
  
  
  The controller has the ability to map an LBA address to different    physical locations on the flash. The controller uses a mapping table
  to keep track of the relationship between the logical block and the
  physical address
  The presence of spare blocks on the flash for replacement of blocks    that contain invalid data
  
  
  Updated or new data is written to an available free block. The block
  that contains old data is erased in the background and then marked as
  a free block. This block rotating technique ensures even wear of
  memory blocks across the flash device. The Wear Leveling process is
  transparent to the operating system.