text: **10.4.1 Introduction to DRPs**
  
  At its core, a DRP uses a Log Structured Array (LSA) to allocate capacity. A log structured 
  array allows a tree-like directory to be used to define the physical placement of data blocks 
  independent of size and logical location. Each logical block device has a range of Logical 
  Block Addresses (LBAs), starting from 0 and ending with the block address that fills the 
  capacity. 
  
  When written, an LSA allows you to allocate data sequentially and provide a directory that 
  provides a lookup to match LBA with physical address within the array. Therefore, the volume 
  you create from the pool to present to a host application consists of a directory that stores the 
  allocation of blocks within the capacity of the pool. 
  
  In data reduction pools, the maintenance of the metadata results in I/O amplification. I/O 
  amplification occurs when a single host-generated read or write I/O results in more than one 
  back-end storage I/O requests because of advanced functions. A read request from the host 
  results in two I/O requests, a directory lookup, and a data read. A write request from the host 
  results in three I/O requests, a directory lookup, a directory update, and a data write. 