Features of the Windows agent

Features of the Windows agent are listed in the following tables.

Feature

OS version

During backup

During restore

Sparse files

Windows 2000 and above

A sparse file is a large file which is not made up of a great deal of data. When the sparse file facilities are used, the system does not allocate hard drive space to a file except in regions where it contains something other than zeros.

Sparse files are backed up in a way that only valid data blocks of the files are stored on the backup media, thus saving space that would otherwise be taken up by zero filled blocks

The data blocks are reconstructed to restore the sparse file in its original form.

Encrypted files

Windows 2000 systems and above (NTFS volumes only).

Windows 2000 and above support encryption of files and folders. Encrypted folders are backed up and restored encrypted.
When backing up encrypted files, the file data is not decrypted; instead, raw encrypted data is read and backed up.

For encrypted files the raw encrypted data that was stored to the backup media is restored back into a file.
Recovery agents may be required in order to access the file if it is restored to a different system.

Hard links

Windows 2000 systems and above (NTFS volumes only).

A hard link is a file system-level shortcut for a given file. When a hard link is created to an existing file, information is added to its directory entry at the NTFS level. The original file now has two or more names that can be used to access the same content.
When backing up such files, the backup engine saves the contents of a hard linked file only once. When it encounters a different name of the linked file that has already been backed up, it simply saves the link between the names instead of saving the contents of the file again.

Since the backup engine saves the information about the links between files, hard links are restored seamlessly, so that the same file contents can be accessed using many names. Restore of a hard link succeeds only if the original file containing the contents already exists on the system. In case that the file referenced by the hard link is not already present in the system, the user is notified that he/she needs to restore the original file first.

Offline files

Windows 2000 systems and above (NTFS volumes only).

Offline files are files whose data is not immediately available. The file data may have been physically moved to offline storage. Remote storage and the hierarchical storage management software support these types of files.
When such a file is backed up, the engine indicates to the system that the file data is requested, but it should continue to reside in remote storage. It should not be transported back to local storage.

Offline files are restored like normal files.

Junctions and volume mount points

Windows 2000 systems and above (NTFS volumes only).

Volume mount points are based on reparse points; they allow administrators to graft access to the root of one local volume.

Similarly, junctions are used to graft a target folder onto another NTFS folder or “mount” a volume onto an NTFS junction point.

The engine follows the reparse point to backup the files/folders of the Volume Mount point.

The engine restores the reparse data that was backed up for a junction or volume mount point. For the restore process to be valid the target directory/volume should also exist in the system.

Compressed files

Windows NT4 systems and above (NTFS volumes only).

On the NTFS volume each file and directory has a compression bit. If this bit is set, all data in the file is compressed. The backup engine backs up uncompressed data on a file.

During restore, the engine marks a file/folder as compressed before data is written to the file. Therefore, when data is restored, the system automatically compresses it and the file/folders are restored in their original compressed state.

Registry aliases

Windows NT4 systems and above.

Registry aliases are links in the registry from one key to another. When a registry link is traversed, the path searching continues at the target of the link.
The backup engine detects these links in the registry and saves these links instead of copying the target key to which they point. Thus, a lot of duplicate data is eliminated from the registry backup and restore process.

The registry aliases are restored as links. The target of the link has to present in order for the link to work correctly.

Registry security information

Windows 2000 systems and above.

The engine provides a mechanism to save the security information related to a registry key. The user can turn this mechanism on or off using the BackupRegSec flag in the master.ini file.

If the security information of the registry keys was backed up then it is reapplied to the keys during a restore process.

Unmounted volumes

Windows XP and above

The unmounted volumes like Microsoft System Reserved partitions are backed up by the engine

The unmounted and reserved volumes are recovered on the restore operation

Additional features of the Windows agent are listed below:

Feature

OS version

During backup

Temporary files

Windows NT4 systems and above (NTFS volumes only)

The engine provides a mechanism to allow the user to exclude temporary files during a backup process. This option can be chosen from the client GUI by selecting the Exclude Temporary Files option in the backup menus.

Once selected, this option will exclude the following:

All files in the Internet cache and the temporary folder of all users in the system.

All files marked with the flag FILE_ATTRIBUTE_TEMPORARY.

All files of the form ~xxx.tmp.

Wild card exclusion

All systems

It is possible for the client side GUI user to specify a path containing wildcards to be excluded. The following steps describe the process:
Select Backup > Master/Selective > Exclude Files.

Specify the wildcard path in the Filter edit box.

No other file in the list box can be selected.

Click ADD.

Exclusion of files

Windows 2000 systems and above.

The engine maintains a list of files and folders that are excluded from a backup or a restore process. This list contains files such as the page file, temporary files, etc.

Controlling automatic shutdown for reboot

All systems.

A flag in the windows local master.ini file called EnableAutomaticRestart can be specified to control automatic restart behavior. This flag can be set to either Yes or No.
At the end of a restore process, if a reboot is required, a dialog box is presented to query whether the engine should reboot the system. If the dialog box times out without a response, then the status of the flag is used to resolve if the system should be automatically restarted.