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Backing Up Windows Systems
Chapter 5 171
The advantages of the VSS filesystem backup are the following:
• A computer can be backed up while applications and services are
running. Therefore, the applications can continue writing data to the
volume during a backup.
• Open files are no longer skipped during the backup process, because
they appear closed on the shadow copy volume at the time of the
shadow copy creation.
• Backups can be performed at any time without locking out users.
• There is little or no impact on performance of the application system
during the backup process.
For VSS filesystem backup related options, refer to “Using Backup
Options” on page 225. Also refer to the HP OpenView Storage Data
Protector Concepts Guide for details on the VSS concepts.
Reparse Points Basically, reparse points are plain filesystem objects with a unique tag
attached, known as a reparse point ID. The NTFS 3.x directories or files
can contain a reparse point, which typically imitates the contents by
directing to data from another location.
When Data Protector encounters reparse points, the reparse point IDs
are not followed by default, what is also known as backing up raw
reparse points. This affects the way you configure your backups:
✓ If you configure a backup using Disk Delivery, all data will be backed
up once.
✓ If you back up filesystems or drives containing reparse points, ensure
that the data pointed to by a reparse point gets backed up. For
example, the Windows 2000/XP/Server 2003 directory junctions
reparse points are not followed, so the junctions have to be backed up
separately. SIS reparse points are exceptions.
The Single Instance Storage (SIS) service regularly checks the
files on a disk. If the service detects several identical files, it replaces
them with the reparse points and stores the data into a common
repository. In this way, the disk space usage is reduced.
Reparse points let you mount logical volumes as disk drives. Data
Protector treats the mounted volumes as though they were ordinary
drives, so that they are visible as selectable objects for backup.