77. NTFS Compressed Files

• NTFS is capable of compressing

  • individual files

  • all files within a folder

  • all files/folders on the volume.

• Compression is executed within NTFS.

• Any Windows program can read/write compressed files without considering the extent of the compression.

• When a compressed file is opened, only a part of the file is decompressed while being read.

• Data already in memory is uncompressed.

• Modified and new data is compressed again -- when written to the compressed file on disk.

• NTFS compression algorithms support cluster sizes of up to 4 KB.

• The best use of compression is for files which are repetitive, written seldom, usually accessed sequentially: log files are an ideal example.