File Attributes
  File Attributes

File Attributes are bits of information that are stored in the file directory along with information such as the file name and size.

FileWizard can read and change the following file attributes"

Read-Only  most software, upon seeing a read-only file will refuse to delete or modify it.  "Access Denied" is a DOS response to a read-only file.  Windows Explorer will present a message
"The file 'dummy 1.doc' is a read-only file. Are you sure you want to move it to the Recycle Bin?"

Hidden  A hidden file will not be displayed by the DOS "DIR" command unless a special flag is used.  Windows Explorer will display hidden files if you so designate in ControlPanel/FolderOptions/View.

You can choose to hide a file or folder using the selection in the Properties window in Windows Explorer.

System This flag is used on files that are used by the system and should not be modified or removed from the disk.  You could look at this as a more serious "read-only" flag.

Archive This bit is used by backup software to indicate whether the file has been backed up.  When a file is modified, the Archive bit is set, and when the file has been backed up, the Archive bit is cleared.  It is by use of the Archive bit that incremental backups are possible.

Compressed 

NTFS Compression

NTFS compression is available on volumes that use the NTFS file system, and NTFS compression has the following features and limitations:
• You can use NTFS compression to compress individual files and folders, as well as an entire NTFS volume.
• You can compress a folder without compressing its contents.
• You can work with NTFS-compressed files without decompressing them, because they are decompressed and recompressed without user intervention.
• You can display NTFS-compressed file and folder names in a different color to make them easier to identify.
• You may notice a decrease in performance when you work with NTFS-compressed files. When you open a compressed file, Windows automatically decompresses it for you, and when you close the file, Windows compresses it again. This process may decrease your computer performance.
• NTFS-compressed files and folders only remain compressed while they are stored on an NTFS Volume.
• You cannot encrypt an NTFS-compressed file.

With FileWizard actions you can compress or uncompress a file.

Sparse
A sparse file has an attribute that causes the storage subsystem to allocate only meaningful (nonzero) data. Nonzero data is allocated on disk, and non-meaningful data (large strings of data composed of zeros) is not. When a sparse file is read, allocated data is returned as it was stored; non-allocated data is returned, by default, as zeros.

NTFS deallocates sparse data streams and only maintains other data as allocated. When a program accesses a sparse file, the file system yields allocated data as actual data and deallocated data as zeros.

NTFS includes full sparse file support for both compressed and uncompressed files. NTFS handles read operations on sparse files by returning allocated data and sparse data. It is possible to read a sparse file as allocated data and a range of data without retrieving the entire data set, although NTFS returns the entire data set by default.

With the sparse file attribute set, the file system can deallocate data from anywhere in the file and, when an application calls, yield the zero data by range instead of storing and returning the actual data. File system application programming interfaces (APIs) allow for the file to be copied or backed as actual bits and sparse stream ranges. The net result is efficient file system storage and access. Next figure shows how data is stored with and without the sparse file attribute set.

How to use FileAttributes in storage management

  • You could scan for the file attributes of System, Hidden, and Read-Only to get a quick view of space that you will want to be cautious about deleting.
  • Scan for files with the Compressed bit set to determine how much space has already been compressed and see what space could be obtained by compressing.
  • Archive bit will let you know  your exposure to data loss.  (If the archive bit is on, the file has not been backed up)
  • Sparse files should be managed carefully.  If a sparse file is moved to a disk that does not support sparse files, what was stored as a sparse file of 100MB could take many GigaBytes to store.

For more information on FileAttributes see: http://www.pcguide.com/ref/hdd/file/fatAttributes-c.html

Sparse files

http://www.ntfs.com/ntfs-sparse.htm

Compression

http://support.microsoft.com/kb/307987

Archive

http://www.answers.com/topic/archive-attribute

System, Hidden

http://www.pcguide.com/ref/hdd/file/fatAttributes-c.html

Read-Only

http://www.worldstart.com/tips/tips.php/269

 

   

 

 


Last updated 11/11/2009
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