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Shadow copy RRS feed

  • Question

  • Hi

    We are using Windows WBADMIN utility to take backup. From some articles I came to know that this utility uses volume shadow copy to take backup.

    Can anyone explain me the exact steps it follows.?

    Is this shadow copy is stored persistently or it deletes it after taking a backup.  (Its required for incremental backups next days according to me).

    Is this shadow copy visible to users? if yes, how.  How much space this shadow copy will occupy.

    I know I've overshooted questions but these things are not clear to me :(

    thanks in advance.

    Tuesday, March 8, 2011 9:40 AM

Answers

  • Hello,

    WBADMIN is command-line utility to create backups using WBENGINE service. This is the engine that is part of Windows Server Backup feature in server SKUs and is also part of the system image backup feature in client SKUs.

    Backups created by WBADMIN uses shadow copies in the following ways:

    1. On the source volume, the shadow copy created by backup is used to read the data to be backed up.

    2. In case entire volume is included in backup (say B1) the shadow copy taken is not deleted at the end of the backup. This is to enable the next backup (say B2) to be incremental. At the end of next backup, the shadow copy created by B1 is deleted as it is no longer required.

    3. Shadow copies are created on the backup target (in case target is a volume/disk) at the end of every backup. These are used for providing multiple versions of backups.

    The shadow copies are visible - but they are not exposed to users through Windows Explorer or other such user interfaces. If you run "vssadmin list shadows" from elevated command prompt you can see them. However since shadow copy volumes do not have drive-letters & are read-only they cannot be used as extensively as other volumes.

    The space occupied by shadow copy depends on the amount of churn that happens on the volume. For more information about shadow copies, you can read the following: http://en.wikipedia.org/wiki/Shadow_Copy

    Thanks,

    Sriram [MSFT]

     

     

     


    Sriram [MSFT]
    Tuesday, March 8, 2011 12:30 PM

All replies

  • Hello,

    WBADMIN is command-line utility to create backups using WBENGINE service. This is the engine that is part of Windows Server Backup feature in server SKUs and is also part of the system image backup feature in client SKUs.

    Backups created by WBADMIN uses shadow copies in the following ways:

    1. On the source volume, the shadow copy created by backup is used to read the data to be backed up.

    2. In case entire volume is included in backup (say B1) the shadow copy taken is not deleted at the end of the backup. This is to enable the next backup (say B2) to be incremental. At the end of next backup, the shadow copy created by B1 is deleted as it is no longer required.

    3. Shadow copies are created on the backup target (in case target is a volume/disk) at the end of every backup. These are used for providing multiple versions of backups.

    The shadow copies are visible - but they are not exposed to users through Windows Explorer or other such user interfaces. If you run "vssadmin list shadows" from elevated command prompt you can see them. However since shadow copy volumes do not have drive-letters & are read-only they cannot be used as extensively as other volumes.

    The space occupied by shadow copy depends on the amount of churn that happens on the volume. For more information about shadow copies, you can read the following: http://en.wikipedia.org/wiki/Shadow_Copy

    Thanks,

    Sriram [MSFT]

     

     

     


    Sriram [MSFT]
    Tuesday, March 8, 2011 12:30 PM
  • Thanks for the reply...

    Wednesday, March 9, 2011 2:26 AM
  • Hi,

    I've doubt again :(

    Say I took full back up on Monday, and next days, till sunday,  I take incremental system backup daily.

    This will have shadow copy in the back up drive as you said.

    Now if I take full backup on next Monday, will it delete the old shadow copy and create a fresh or it will just add the modified content from Sunday till next Monday?

    thanks in advance.

    Wednesday, March 9, 2011 6:06 AM