Disk Size Manager 

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Notes on NTFS

There are some peculiarities of Disk Size Manager work with the NTFS, a file system that can be used with the operating system Windows NT/2000 or later. 

Files/folders access
A user under Windows NT/2000 can limit the access of other users to his/her files and folders granting or denying certain rights like reading, writing, executing or deleting files. Even the Administrator can be denied access to certain files or folders. 

However Disk Size Manager is still capable of scanning such folders if you are logged in as Administrator or as a user that has the right to perform backups (you can set this option with the user editor in Windows NT or at Control Panel\Administrative Tools\Local Security Policy in Windows 2000).

File-based compression
NTFS supports data compression on an individual file basis. Compressed files can be read and written to/from an NTFS volume without being previously decompressed with another application. Decompression occurs automatically during the access to the file. The file is re-compressed when it is closed or saved.

The space occupied by a compressed file is usually much smaller than the file’s normal size. As a consequence, for folders that are partially or completely compressed, the allocated space reported by Disk Size Manager may be smaller than the size reported for this folder. Disk Size Manager is able to show the compression ratio in the corresponding column in the Details view (the button “Details” in the main toolbar). 

The NTFS version for Windows 2000 supports a concept that is similar to compressed files: sparse files. Files which are large but only partially used are called sparse files. The operating system does not allocate disk space for the unused parts of a sparse file, so it occupies less disk space than its actual size is. Disk Size Manager treats sparse files like compressed files and also calculates the compression ratio for them.

Volume mount points and symbolic links (reparse points)

For Windows 2000 and later NTFS supports reparse points - volume mount points and symbolic links. 

A volume mount point is an existing path where another volume is "mounted". Users and applications can refer to the mounted volume using this path. This allows you to unite distributed folders into a solid logical system. 

Symbolic links work similar: assume you have an empty folder C:\Files\Contracts. You can create a symbolic link to D:\Reports in it. Then accessing C:\Files\Contracts the folder applications will then see there the contents of D:\Reports.

When you are scanning an NTFS volume via network (Windows NT/2000 client), Disk Size Manager is able to handle file based compression and reparse points correctly. Since the mounted and linked folders are not physically stored on the drive you are scanning, their size is not counted into the drive’s total volume. The mounted folders and symbolic links are shown in gray color.

Note. Volume mount points and symbolic links are not supported in Windows 9x.