Write short note on compression regarding the file system in Windows 2000.
NTFS is able to perform data compression on individual files or on all data files in a directory. To reduce a file NTFS divides the file's data into compression units which are blocks of 16 contiguous clusters. When every compression unit is written a data compression algorithm is applied. If the result fits into less than 16 clusters the compressed version is stored. When reading NTFS is able to determine whether data have been compressed and if they have been the length of the stored compression unit will be less than 16 clusters. To get better performance when reading contiguous compression units NTFS decompresses and prefetches ahead of the application request.