1. A method of operation for a nonvolatile memory system, the method comprising: selecting a source block from among a plurality of memory blocks in the nonvolatile memory system; and performing a reclaim operation for the source block based on a number of program and erase (P/E) cycles which have been performed on the source block, including when the number of P/E cycles which have been performed on the source block is a first value, performing the reclaim operation for the source block at a first speed, and when the number of P/E cycles which have been performed on the source block is a second value greater than the first value, performing the reclaim operation for the source block at a second speed which is faster than the first speed.