Windows 2000 Administration in a Nutshell

Name

compression

Synopsis

A method for reducing the disk space required on NTFS volumes.

Description

Files and folders stored on NTFS volumes can be compressed to minimize the amount of disk space they occupy. When these files are accessed, the operating system uncompresses them automatically so they can be read or modified; when the modified files are saved or closed, they are automatically compressed again. The whole process is transparent to the user.

Both files and folders can be compressed. If a folder is compressed, the files within it need not be compressed—or some may be and others not.

Notes

• For information on how to compress files and folders, see files and folders .

• Certain file types can be effectively compressed, resulting in significant gains in disk space, while compressing other file types shows little gain in space. For example, a compressed bitmap (.bmp ) may need only 25% or less of its uncompressed space, while compressing a binary executable program file (*.exe) rarely results in a significant gain in space. You should not try to compress files that are already compressed, such as WinZip (.zip) files. This simply results in wasted processing power.

• You must have NTFS write permission on a file or folder in order to compress it.

• In order to compress a file, you need enough free space on the disk to hold the file in both its compressed and uncompressed state.

• When a file is copied from one place to another, it is first uncompressed, copied, and then compressed again. If ...