Managing+Compression

toc Windows XP Professional has 2 kinds of compression: Compressed Folders and NTFS compression.

=Compressed Folders=

To users of other & older operating systems, you may have used software to create ZIP files. Compressed Folders is the integration of ZIP files into the operating system. This feature was introduced in Windows XP

To make a Compressed Folder, use Windows Explorer. Click File, click New, and click Compressed (Zipped) Folder.

Here's what a Compressed Folder looks like in Windows Explorer:

[| Benefits] include:
 * works across FAT and NTFS volumes
 * can open files directly from inside a compressed folder (no uncompressing required)
 * they're compatible with any computer that can read zip files
 * they're encryptable
 * compressing doesn't decrease performance

Note: Compressed Folders is not the same as NTFS Compression, which is explained below.

=NTFS Compression=

As the name implies, this is a feature of NTFS. Compress/uncompress happens invisibly, so the user doesn't have to go through a uncompress step to access data in a file.

Tricky bit: NTFS still has to allocate disk space based on the file's uncompressed size.

Howto Compress Files and Folders
In Windows Explorer, right click a file or folder, choose Properties then click on the Advanced button. Toggling compression on and off requires the Write permission.

The contents of a folder aren't necessarily compressed. If you choose to compress a folder with stuff in it, you get a dialog box that asks you if you want to compress everything in the folder.

Extra: [|Compact] is a Windows XP command line tool for working with compression.

Howto Compress Drives and Volumes
Windows Explorer, right click the drive (C:\ in my case), click Properties.

Display Compressed Files/Folders in Another Color
Default: compressed files/folders are blue. To change this, in Windows Explorer, click Tools menu, click Folder Options. In Folder Options, click View tab, toggle the Show Encrypted Or Compressed Files In Color.

Copying & Moving + Compression
Note: copying compressed files can be slow because the file has to be uncompressed, copied, and recompressed.
 * On the same volume
 * Copy: Inherits compression from target folder
 * Move: Retains initial compression state
 * To another NTFS volume
 * Copy: Inherits compression from target folder
 * Move: Inherits compression from target folder
 * To a FAT volume: uncompresses always because compression isn't supported on FAT volumes
 * To a floppy: uncompresses always

NTFS Compression Tips
Microsoft.com XP Documentation: [|Benefits] (NTFS vs. Compressed Folders).

Best practices:
 * Compress infrequently accessed data because compressing/uncompressing uses system overhead, which you want to limit.
 * Don't compress compressed files (zip files) because the system will spend time trying to compress something that can't be compressed.
 * Compress file types that compress well (for example, bitmap images can be compressed to less than 50% their original file size).
 * Don't compress files/folders that need to be copied or moved frequently because of the additional overhead incurred in the uncompress, copy, recompress cycle.

=Links=

[|BlackViper's XP File and Folder Compression Guide]: a side-by-side comparison of both types of compression offered by XP. Interesting note: Compressed folders usually squeeze their contents smaller while NTFS compression is faster.

[|Is it worth using NTFS compression?] This blogger says no.