create barcode labels c# Unused Space 20 GB Data File in C#

Maker Quick Response Code in C# Unused Space 20 GB Data File

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Figure 20-5.

Stored normally, the file would use 20 GB of space on the volume. If you mark the file as sparse, however, NTFS allocates space only for actual data and marks empty space as nonallocated. In other words, any meaningful or nonzero data is marked as allocated and written to disk, and any data composed of zeros is marked as nonallocated and is not explicitly written to disk. In this example, this means the file uses only 5 GB of space, which is marked as allocated, and has nonallocated space of 15 GB. For nonallocated space, NTFS records only information about how much nonallocated space there is, and when you try to read data in this space, it returns zeros. This allows NTFS to store the file in the smallest amount of disk space possible while still being able to reconstruct the file s allocated and nonallocated space.

Microsoft Windows Server 2003 Inside Out In theory, all this works great, but it is up to the actual program working with the sparse file to determine which data is meaningful and which isn t. Programs do this by explicitly specifying the data for which space should be allocated. In Windows Server 2003, several services use sparse files. One of these is the Indexing Service, which stores its catalogs as sparse files. Using the FSUTIL SPARSE command, you can easily determine whether a file has the sparse attribute set. Type fsutil sparse queryflag FilePath at the command prompt, where FilePath is the path to the file you want to examine, such as

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You can examine sparse files to determine where the byte ranges that contain meaningful (nonzero) data are located by using FSUTIL SPARSE as well. Type fsutil sparse queryrange FilePath at the command prompt, where FilePath is the path to the file you want to examine, such as

sparse range [0] [28672]

In this particular case, the output specifies that there s meaningful data at the start of the file to byte 28672. You can mark files as sparse as well. Type fsutil sparse setflag FilePath at the command prompt, where FilePath is the path to the file you want to mark as sparse.

File-based compression allows you to reduce the number of bits and bytes in files so that they use less space on a disk. The Windows operating system supports two types of compression: NTFS compression, which is a built-in feature of NTFS, and compressed (zipped) folders, which is an additional feature of Windows available on both FAT and NTFS volumes.

Windows allows you to enable compression when you format a volume using NTFS. When a drive is compressed, all files and folders stored on the drive are automatically compressed when they are created. This compression is transparent to users, who can open and work with compressed files and folders just as they do with regular files and folders. Behind the

Managing Windows Server 2003 File Systems scenes, Windows decompresses the file or folder when it is opened and compresses it again when it is closed. Although this can decrease a computer s performance, it saves space on the disk because compressed files and folders use less space. You can turn on compression after formatting volumes as well, or if desired turn on compression only for specific files and folders. Once you compress a folder, any new files added or copied to the folder are compressed automatically and they remain compressed even if you later move them to an uncompressed folder on an NTFS volume. Moving uncompressed files to compressed folders affects their compression attribute as well. If you move an uncompressed file from a different drive to a compressed drive or 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. Finally, if you move a compressed file to a FAT16 or FAT32 volume, the file is uncompressed because FAT16 and FAT32 volumes do not support compression. To compress or uncompress a drive, follow these steps: