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Compressed Folders

The next new interface feature we'll look at is compressing files and folders. This provides the utilitarian function of saving disk space by reducing the amount of physical disk space occupied by files. Windows NT has always had a mechanism for saving disk space by compressing files: the NTFS file compression attribute feature. With Windows Server 2003, Microsoft introduces another method for compressing files—the Compressed (zipped) Folders feature. The following sections discuss these two mechanisms and how they differ.

NTFS Folder Compression

NTFS file and folder compression is implemented as a file-level attribute. A check box in the properties of a volume, folder, or file designates it as compressed. If this attribute is enabled, the operating system handles the compressing and uncompressing of the file without any user intervention. Whenever a file or folder with the compressed attribute enabled is opened, the operating system automatically uncompresses it. When the file is saved, the operating system automatically compresses it again, completely transparently to the user. However, all this compressing and uncompressing of files adds extra processing overhead because the operating system has to constantly uncompress and recompress files whenever they're opened and closed. When determining whether to use NTFS compression, you need to balance the benefits of freeing up disk space and ease of use for the user must against the extra processing load.

Another drawback of NTFS compression is that, because it is a file system attribute, the compression occurs only on the file system. The implication of this is that if you access the file across the network, it is first uncompressed by the operating system and then sent across the network in an uncompressed format. Thus, no network bandwidth improvement occurs because the file is sent across the network as if it were never compressed. In actuality, degradation in the file transfer occurs because of the extra processing required to uncompress the file.

Yet another drawback of NTFS compression is that it is incompatible with the Encrypting File System (EFS) NTFS attribute introduced in Windows 2000. You can enable either the file compression attribute or the file encryption attribute, but not both.

For more information about EFS, see "Encrypting File System."

File Compression

To compress a file, you need to have available at least as much disk space as the uncompressed file requires. For example, if you attempt to copy a 100MB file to a compressed location with 80MB free, even if the file can be compressed to 50MB, you will be unable to copy the file because it must be copied first and then compressed.

The Compressed (Zipped) Folders Feature

Windows Server 2003 still has the NTFS file compression attribute, just like previous versions do. However, it now also has the Compressed Folders feature. This feature is akin to third-party compression utilities such as WinZip or its earlier cousin PKZIP. As shown in Figure 3.1, Compressed Folders is implemented as a pop-up menu option. You just select the files or folders you want to compress, right-click, select Send To, and then select Compressed (Zipped) Folder.

Figure 3.1Figure 3.1 You can right-click a file or folder to create a Zip file with the new Compressed Folders feature.

This creates a separate (Zip) file containing all the files and folders you selected. You can use this new feature to individually compress files and folders for archival purposes. Unlike NTFS file compression, though, user intervention is required to compress and uncompress the files with this method. Compressed Folders really creates compressed copies of the file(s), whereas NTFS compression compresses the original file. In addition, because a utility is doing the compression rather than a file-level attribute causing compression, you can compress any file or folder—even those on FAT partitions. The true benefit of the Compressed Folders feature is the ability to move the Zip archive that is created elsewhere, such as across the network. This means you have the capability to transport files in a compressed format. You can therefore minimize your network traffic when copying an archive to another location or make it small enough to fit on some other archival medium, such as CD-ROM, zip, or floppy disk, for transport elsewhere. These are just a couple examples of the uses of Compressed Files. Another common use is to compress multiple files and wrap them up in a single package, which is particularly useful for emailing large documents or pictures to friends or support personnel.

Working with Zip Files

In addition to providing you the ability to create and read your own Zip files, the Compressed Folders feature enables you to extract Zip archives—even those created with other Zip applications.

Web Resource

For a comparison of the Compressed Folders feature and third-party compression utilities such as WinZip, go to http://www.deltaguideseries.com and search for article ID A010301.

Compressed Folders on 64-Bit Windows Server 2003

The Compressed Folders feature is not available on 64-bit versions of Windows Server 2003.

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