Leider gibt mir keiner dieser Links die Antwort auf meine konkrete Frage. Habe auch schon einige Bücher und Webseiten angesehen....
Hier noch einmal im Detail:
Backup Version and Space Management in Windows Server Backup
http://blogs.technet.com/b/filecab/archive/2009/06/22/backup-version-and-space-management-in-windows-server-backup.aspx
[..]
If the backup storage location is full, Windows Server Backup automatically deletes the oldest backup version to make space for the current backup. Since each backup is stored inside a shadow copy, deleting a backup version is accomplished by simply deleting
the corresponding shadow copy. However, space for a system state backup in Windows Server 2008 is not automatically managed by Windows Server Backup. See the section “How to Delete System State Backups” below for managing system state backups in
Windows Server 2008.
[..]
Windows Server Backup uses the .vhd format for writing backups. The current virtual hard disk specification limits the size of a virtual hard disk to be 2040 GB, which can fit a volume of size 2040 GB – 2 MB, (i.e., 2088958 MB). Windows Server Backup
in Windows Server 2008 also limits the maximum source volume size to be 2088958 MB. In Windows Server 2008 R2, if you are not backing up a full volume and, instead, creating a backup of selected files/folders, your source volume size can be more than 2088958
MB, provided your actual data size is less than equal to 2088958 MB. If you are creating a full volume backup, the maximum source volume size limit continues to be 2088958 MB.
[..]
Windows Server Backup automatic disk usage management
http://blogs.technet.com/b/filecab/archive/2011/03/14/windows-server-backup-automatic-disk-usage-management.aspx
[..]
Automatic disk usage management
After you configure a disk for a scheduled backup, Windows Server Backup automatically manages the disk usage—you do not need to be concerned about running out of disk space after repeated backups. Windows Server Backup will automatically reuse the
space occupied by older backups when creating new backups. The management tool displays the backups that are available as well as the disk usage information. This can help you plan for provisioning additional storage to meet your recovery objectives.
[..]
How does it work?
Automatic Disk usage management feature comes into play when Windows Server Backup detects that the backup target does not have enough space to accommodate the backup while backup is in progress. The way Windows Server Backup creates space for new backup is
by shrinking the storage space allocated for snapshots (called diff area). As a result, one or more older snapshots (and hence backup versions corresponding to those snapshots) occupying the diff area that got shrunk get deleted. Before shrinking diff area,
WSB determines whether shrinking the diff area can free up the requisite space so the backup can happen. If enough free space can get created, WSB goes ahead with the shrinking and continues with the backup. WSB will not shrink the diff area to less
than 1/8 of Target volume size as we do not want to lose all past backups just to accommodate this one. This is why sometimes backup fail with target out of disk space in spite of automatic disk usage management feature in Windows Server Backup.
Criteria:
This feature will not work if Windows Server Backup has reached the state where it cannot further contract the snapshot allocated space and also preserve some of the existing backups. This happens when space required to complete the backup causes the snapshot
storage space to become less than 1/8 of the target size. You can change the snapshot storage from here: Volume -> properties -> shadow copies -> settings.
If the Automatic Disk usage management criterions are not satisfied, you can still delete old backups created by Windows Server Backup.
[..]
--
Tobias Redelberger
System & Support Engineer
StarNET Services
(HomeOffice Berlin)
Frankfurter Allee 193
D-10365 Berlin
Germany
Mobil: +49 (163) 84 74 421
Email: T.Redelberger@starnet-services.net
Web: http://www.starnet-services.net
