Super block maintains the list of free disk blocks in the Unix file system. The super block contains an array of free disk block numbers, one of which points to the next entry in the list. That entry in turn will be a data block, which contains an array of some other free blocks and a next pointer. When process requests for a block, it searches the free block list returns the available disk block from the array of free blocks in the super block. If the super block contains only one entry which is a pointer to a data block, which contains a list of other free blocks, all the entries from that block will be copied to the super block free list and returns that block to the process.