| Compression can only be set on NTFS-volumes. |
| Windows 2000 does not support DriveSpace, Double Space etc. |
| Encrypted files cannot be compressed. |
| The pagefile cannot be compressed. |
| The maximum cluster size allowed for compression is 4,096 bytes. Otherwise the message 'File system does not support encryption' will appear. |
Files can be compressed via the Explorer. Select the file/folder and it's properties. Press the Advanced button on the General-tab and (un)select 'Compress contents to save disk space'. After pressing the Ok-button when compressing a folder, you will be asked to compress only this folder and files or also the sub folders and files.
Use Tools, Folder options to display compressed files and folders in a different color. The default color is blue. This color can be changed in the registry. (or via TweakUI)
Files can also be compressed by using compact.exe. Compact utility options :
| /c Compresses the specified folder or file. (incl. hidden- and systemfiles) |
| /u Uncompresses the specified folder or file. (incl. hidden- and systemfiles) |
| /s[:\DirName] applies the action to all subfolders of the specified folder, or to the current folder if none is specified. If :\DirName is used, the folder attribute is not altered. |
| /i Ignores errors. |
| /f Forces the action on files that are already compressed. |
| /a Display files with the hidden- and/or system attribute. |
| /q Displays minimal information. |
Compression runs more efficiently under Windows 2000 Professional than Windows 2000 Server. Heavily loaded folders with lots of write-traffic should not be compressed. Servers that mostly read data will not experience significant performance degradation. Programs that use transaction logging and constantly write to a database or log should not store their files on a compressed volume. as it can produce "dirty" pages faster than the mapped writer can write them.
Microsoft does not recommend that user's home folders and roaming profiles be placed on a volume that is using NTFS compression because of the large number of reads and writes performed.
NTFS uses the Lempel_Ziv compression scheme.
Manually compressing the Offline Files cache\database (the %SystemRoot%\CSC folder) works, and files currently stored in the cache are compressed, but newly cached files are not stored in compressed format and previously compressed files become uncompressed after synchronization.
Offline file compression is not supported. Windows 2000 writes files in uncompressed format even if the folder is marked for compression. Marking the CSC (Client Side Caching) folder to be compressed and leaving it this way can cause a variety of complications ranging from caching update problems to Windows 2000 not responding while attempting to access files residing within the cache.
If a file is moved within the same partition, the compression-attributed is kept. (independent of the directory to which the file is copied) If a file is copied or moved to another partition, it takes of the compression attribute from the folder it is moved or copied to.
| Enterprise class storage |
| More information about Lempel-Ziv compression |
| Search for 'compress' in knowledge base |
| Search for 'compression' in knowledge base |
Last update : 9 October 2000