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Definitive Definition of vssFul RRS feed

  • Question

  • Sorry to ask this again, but I continue to find explanations of WBAdmin's vssFul parameter to be incomplete and semi-ambiguous.

     

    1. Using -vssFul resets the archive bit on all files backed up in the current backup?

    To be clear, if a partition is not included, its files archive biit will not be touched?

    If -vssful is not used, no archive bits will be touched?

     

    2. WBAdmin will or will not backup only files that have the archive bit set. True or False?

    To be clear, does WBAdmin always backup files in a partition whether or not the archive bits are set? Does WBAdmin itself care if the archive bits are set?

     

    3. When creating alternating daily backups with WBAdmin only (no 3rd party software), what impact is there on the use of -vssFul?

    To be clear, with or without -vssFul, can any backup in a rotation be used to restore partitions?

     

    4. Is there any difference in the implementation between WBAdmin's -vssFul parameter between Os's (Vista/W7, W2K8/W2K8-R2). Have there been any changes in service packs? Any difference in 32/64 bit?

     

    5. What differences (if any) are there with Windows Server Backup. What about when using Windows Server Backup for internal backups and WBAdmin for removable drive or network share backups?

     

    Thanks,

    Bob.

    Wednesday, September 15, 2010 2:46 PM

Answers

  • Hello,

    Before I try to answer your questions, wanted to clarify few things upfront.

    - VSSFull parameter that you can specify through WBADMIN does not have any connection with the archive bit of files being backed up. Windows Server Backup (WSB) uses VSS technology to create shadow copies on the source volumes for backup. As part of this, we ensure all VSS writers that report files on these volumes are involved in the shadow copy. This is to make sure that the backup is not only crash-consistent but also consistent with respect to the applications having VSS writers and residing on those volumes. The VSSFull parameter is a way of letting the VSS application writers know whether the backup is a full backup or incremental. Based on this the writers would do application specific processing. (e.g. SQL VSS writer will truncate the log files involved in backup etc.) Please refer to the following documentation about VSS backup flags for more information:

    http://msdn.microsoft.com/en-us/library/aa384679(VS.85).aspx

    (WSB treats VSSFull input to pass VSS_BT_FULL as backup type to VSS)

    - Windows Server Backup does not update archive bit for files that it backs up. There are backup applications that do this to track which files need to be included for subsequent incremental backups but in general this approach is not fool proof. (file's archive bit could bget set in many other ways that backup cannot control). Windows Server Backup instead relies on the USN journal to track file changes to include in incremental backup.

    Please see answers to your questions inline.

    1. Using -vssFul resets the archive bit on all files backed up in the current backup?

    >> No. For file system, there is no VSS writer. So if there are files that are not part of any application included in backup, then VSSFull does not have any impact on them.

    To be clear, if a partition is not included, its files archive biit will not be touched?

    >> Like I said before, WSB doesn't alter archive bit in any case.

    If -vssful is not used, no archive bits will be touched?

     >> Pl. see answer above.

    2. WBAdmin will or will not backup only files that have the archive bit set. True or False?

    >> WSB/WBAdmin doesn't honor archive bit setting.

    To be clear, does WBAdmin always backup files in a partition whether or not the archive bits are set? Does WBAdmin itself care if the archive bits are set?

    >> See answer above.

     

    3. When creating alternating daily backups with WBAdmin only (no 3rd party software), what impact is there on the use of -vssFul?

    To be clear, with or without -vssFul, can any backup in a rotation be used to restore partitions?

    >> See my explanation at the beginning of my reply.

    4. Is there any difference in the implementation between WBAdmin's -vssFul parameter between Os's (Vista/W7, W2K8/W2K8-R2). Have there been any changes in service packs? Any difference in 32/64 bit?

    >> No difference. 

    5. What differences (if any) are there with Windows Server Backup. What about when using Windows Server Backup for internal backups and WBAdmin for removable drive or network share backups?

    >> For backups taken to internal disks, WSB supports all features - file backup/recovery, multiple versions etc.

    For backups taken to removable drive, WSB supports only full volume backup/full volume restore without support for multiple versions.

    For backups taken to network share, WSB supports file backup/recovery but does not support multiple versions.

    Thanks,

    Sriram [MSFT]

    Sunday, September 19, 2010 3:52 AM