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Vortex
Joined: 01 Jan 2008
Posts: 81
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 Posted: Mon Jan 11, 2010 10:02 pm Post subject: Using the volume shadow copy service to access locked files |
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Here is my new tool vscopy.exe , the volume shadow copy creator for Windows XP.
The volume shadow copy feature is a service to make a consistent backup of a volume. Accessing the volume shadow copy, you can copy files locked by the operating system and even backup a complete volume. The volume shadow copy ( VSC ) has an attribute of read-only and just one VSC instance per volume can be created. Windows XP cannot create persistant shadow copies surviving reboots.
The tool takes three command line parameters :
| Code: | | vscopy <volume_letter> <assigned_letter> <file_to_execute> |
The volume_letter represents the volume from which you wish to create the volume shadow copy.
The assigned_letter parameter is the letter assigned to the volume shadow copy. The symbolic name of a volume shadow copy is like the following :
| Code: | | \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy1 |
Assigning a letter to this path makes easier the access to the volume shadow copy.
The file_to_execute parameter can be any batch, .vbs or exe file handling the volume shadow copy. For example, a batch file named backup.bat could access the VSC to copy locked files.
Example usage:
| Code: | | vscopy.exe C: M: test.bat |
C: is the volume selected to shadow copy.
M: is the letter assigned to the volume shadow copy.
Test.bat is a batch file to read the content of the VSC.
A typical output of the tool :
| Quote: | Volume shadow copy path = \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy1
Snapshot release status = 0x0 |
Notice that the release status displaying a value of 0x0 indicates that the resources used by the VSC service is released successfully.
Test.bat can be coded to view the content of the VSC fixed to be “persistant” for a while :
| Code: | @echo Assign a second letter to the VSC to view it via Windows Explorer
subst R: M:\
explorer R:
@echo Wait while the user reads data from the VSC
Pause
subst /D R:
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Notice that this version works only on Windows XP as the methods exposed by the IvssBackupComponents interface are different across
different versions of Windows.
As I mentioned above, a typical usage of the volume shadow copy service is to access locked files. Another example, copying the current user hive
of the registry, copy_ntuser_dat.bat
| Code: | @echo Copy ntuser.dat to the current directory
xcopy "M:\%homepath%\ntuser.dat" . /H /Y
@echo Remove the hidden attribute
attrib -h ntuser.dat |
Another interesting usage of the tool is the complete backup of the system volume with ntbackup. I noticed thatntbackup does not read all the files
in the system directory and restoring the .bkf file in a preinstallation environment like BartPE creates an unbootable volume because of missing files.
The script below can be used to backup the system volume. You can use a BartPE disc to restore the operating system :
Backup_volume.bat
| Code: | C:\WINDOWS\system32\ntbackup.exe backup "@D:\vscopy\Backup_job.bks" /n "Backup.bkf Date: 11.01.2010 , 10:10" /d "11.01.2010 - 10:42" /v:no /r:no /rs:no /hc:off /m normal /j "Backup_job" /l:s /Snap:Off /f "Z:\Backup.bkf"
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Backup_job.bks ( UNICODE file )
| Code: | M:\
M:\RECYCLER\ /Exclude
M:\System Volume Information\ /Exclude |
The only trick in the script is to avoid running ntbackup in volume shadow copy mode as ntbackup is instructed to read the "M volume" containing the
shadow copy. You need to modify the source directory D:\vscopy to run the tool and the destination directory Z:\ to reflect the correct paths in your system.
| Code: | | vscopy.exe C: M: Backup_volume.bat |
http://vortex.masmcode.com/files/vscopy10b1.zip |
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bogdanontanu
Site Admin
Joined: 01 Apr 2006
Posts: 783
Location: Sol, Earth, Europe, Romania, Bucuresti
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| Posted: Tue Jan 12, 2010 8:42 pm Post subject: |
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Hi Vortex,
Thanks for this new and interesting sample.
_________________
Ambition is a lame excuse for the ones not brave enough to be lazy. |
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Vortex
Joined: 01 Jan 2008
Posts: 81
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bogdanontanu
Site Admin
Joined: 01 Apr 2006
Posts: 783
Location: Sol, Earth, Europe, Romania, Bucuresti
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| Posted: Tue Jan 26, 2010 12:14 am Post subject: |
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Thank you again 
_________________
Ambition is a lame excuse for the ones not brave enough to be lazy. |
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