CHANGE THE DRIVE LETTER FOR A VOLUME

10-33Lesson 2 Managing CompressionBACopyMoveRetainsInheritsNTFS volumeCCopy Inherits

F10us17

Figure 10-17

Copying and moving compressed folders and files have different results.

Note When you copy a compressed NTFS file, Windows XP Professional uncompresses the

file, copies the file, and then compresses the file again as a new file. This might take consid-

erable time.

NTFS Compression Guidelines

The following list provides best practices for using compression on NTFS volumes:

■

Because some file types compress more than others, select file types to compress

based on the anticipated resulting file size. For example, because Windows bit-

map files contain more redundant data than application executable files, this file

type compresses to a smaller size. Bitmaps often compress to less than 50 percent

of the original file size, whereas application files rarely compress to less than 75

percent of the original size.

■

Do not store compressed files, such as PKZIP files, in a compressed folder. Win-

dows XP Professional will attempt to compress the file, wasting system time and

yielding no additional disk space.

■

Compress static data rather than data that changes frequently. Compressing and

uncompressing files incurs some system overhead. By choosing to compress files

that are infrequently accessed, you minimize the amount of system time dedicated

to compression and uncompression activities.

■

NTFS compression can cause performance degradation when you copy and move

files. When a compressed file is copied, it is uncompressed, copied, and then

compressed again as a new file. Compress data that is not copied or moved fre-

quently.

Practice: Managing Compression

In this practice, you use NTFS compression to compress files and folders. You uncom-

press a file and test the effects that copying and moving files have on compression. In

the last portion of the practice, you create a compressed folder using the Compressed

Folders feature.

Important In this practice, it is assumed that you installed Windows XP Professional on

the C drive, and that the C drive is formatted with NTFS. If you installed Windows XP Profes-

sional on a different partition and that partition is formatted with NTFS, use that drive letter

when the practice refers to drive C.