78. NTFS Compresion Details

• Compresion works in blocks of 16 clusters

• Data is compressed using a modified LZ77 algorithm, named LZNT1.

• Each block is compressed independently

• If compressed block does not become less than the original 16 clusters, it is left uncompressed.

• Compressing a file adds serious complexity to the way the file is stored.

• The MFT is the only place that contains information about what parts are compressed and by how much.

• If MFT is corrupted there is little hope retrieving the data!

  Reference:
  http://en.wikipedia.org/wiki/LZ77