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When you format a drive for NTFS, Windows 8 allows you to
enable disk compression or file encryption. You use compression to
reduce the disk space that files require, and you use encryption to add
an extra layer of protection to your data.
Disk compression and file encryption are mutually exclusive. You can
use one feature or the other, and neither feature is affected by
BitLocker Drive Encryption, which encrypts disks at the volume level
and protects a computer from external tampering prior to startup of the
operating system.
1. Compressing Drives and Data
With compression, all files and directories stored on a drive are
automatically compressed when they’re created. Because this compression
is transparent to users, compressed data can be accessed just like
regular data. The difference is that you can store more information on
a compressed drive than you can on an uncompressed drive. Note that
File Explorer shows the names of compressed resources in blue.
Note
REAL WORLD Although
compression is certainly a useful feature when you want to save disk
space, you can’t encrypt compressed data. Compression and encryption
are mutually exclusive alternatives for NTFS volumes. You can’t use
both techniques. If you try to compress encrypted data,
Windows 8 automatically decrypts the data and then compresses it.
Likewise, if you try to encrypt compressed data, Windows 8 uncompresses
the data and then encrypts it.
To compress a drive and all its contents, follow these steps:
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In File Explorer or Disk Management, press and hold or right-click
the drive that you want to compress, and then tap or click Properties. -
Select Compress This Drive To Save Disk Space, and then tap or click OK.
Compressing Directories and Files
If you decide not to compress a drive, Windows 8 lets you
selectively compress directories and files. To compress a file or
directory, follow these steps:
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In File Explorer, press and hold or right-click the file or
directory that you want to compress, and then tap or click Properties. -
On the General tab of the Properties dialog box, tap or click
Advanced. In the Advanced Attributes dialog box, select the Compress
Contents To Save Disk Space check box, as shown in Figure 1. Tap or click OK twice.
For an individual file, Windows 8 marks the file as compressed and
then compresses it. For a directory, Windows 8 marks the directory as
compressed and then compresses all the files in it. If the directory
contains subfolders, Windows 8 displays a dialog box that allows you to
compress all the subfolders associated with the directory. Simply
select Apply Changes To This Folder, Subfolders And Files, and then tap
or click OK. Once you compress a directory, any new files added or
copied to the directory are compressed automatically.
Note
If you move an uncompressed file from a different drive to a
compressed folder, the file is compressed. However, if you move an
uncompressed file to a compressed folder on the same NTFS drive, the
file isn’t compressed. Note also that you can’t encrypt compressed
files.
Expanding Compressed Drives
File Explorer shows the names of compressed files and folders in
blue. You can remove compression from a drive by following these steps:
-
In File Explorer or Disk Management, press and hold or right-click
the drive that contains the data you want to expand, and then tap or
click Properties. -
Clear the Compress This Drive To Save Disk Space check box, and then tap or click OK.
Tip
Windows always checks the available disk space before expanding
compressed data. You should, too. If less free space is available than
used space, you might not be able to complete the expansion. For
example, if a compressed drive uses 150 GB of space and has 70 GB of
free space available, you won’t have enough free space to expand the
drive. Generally, you need about 1.5 to 2 times as much free space as
you have compressed data.
Expanding Compressed Directories and Files
If you decide later that you want to expand a compressed file or directory, reverse the process by following these steps:
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Press and hold or right-click the file or directory in File Explorer, and then tap or click Properties. -
On the General tab of the Properties dialog box, tap or click
Advanced. Clear the Compress Contents To Save Disk Space check box. Tap
or click OK twice.
With files, Windows 8 removes compression and expands the file. With
directories, Windows 8 expands all the files within the directory. If
the directory contains subfolders, you have the opportunity to remove
compression from the subfolders. To do this, select Apply Changes To
This Folder, Subfolders, And Files when prompted, and then tap or click
OK.
Tip
Windows 8 also provides command-line utilities for compressing
and uncompressing your data. The compression utility is called Compact
(Compact.exe). The uncompression utility is called Expand (Expand.exe).h
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