How to use DiskShadow for in depth VSS troubleshooting (4034261)

How to use DiskShadow for in depth VSS troubleshooting

VSS troubleshooting is a common task when using AppAssure. Although the VShadow utility is included in the AppAssure Agent Installation directory, there are times when it is preferable to use diskshadow, the Windows utility included in each version of Windows beginning with Windows 2008 as it offers more functionality and a dedicated context. On the other hand, performing common tasks using DiskShadow is sometimes rather counter intuitive, thus the need to organize them in a KB.

1. DiskShadow context
   1. Run diskshadow at an elevated Command or Powershell prompt. The Prompt changes to DISKSHADOW>.
   2. All further commands entered in the console are referring to diskshadow. To quit the context, type exit
2. Logging the results to a text file for further analysis
   1. Launch diskshadow with the "-l" (short from log) parameter
   2. diskshadow -l c:\temp\diskshadow.txt. The log file contains all the context commands and the results displayed on the screen during the session
3. Best Practice and help commands
   1. It is good practice to start every set of DiskShadow commands with reset command and finish with exit
   2. NOTE: Exit quits DiskShadow. Separate multiple jobs using the reset command.
   3. To get more in depth information re the diskshadow capabilities, type help at the diskshadow prompt
   4. More help with specific commands type khelp at the end of the command e.g. Delete Shadows Help
   5. It is recommended to use the logging option as the output may be larger than the screen buffer, thus some data may be lost from the screen.
4. Retrieve VSS providers information
   1. reset
   2. list providers
   3. exit
5. Retrieve detailed VSS Writers information
   1. reset
   2. list writers
   3. list writers status
   4. list writers metadata
   5. list writers detailed
   6. exit
   7. NOTE: Use just one "list" command out of the four "list"  commands shown. The output can use useful to see the list of files which are reported by the VSS writers to be included and excluded by the backup.
6. Test Shadow Creation
   1. reset
   2. set verbose on
   3. set option differential
   4. set context volatile
   5. add volume c:
   6. add volume d: (if the system is on more than one disk, add them one by one)
   7. create
   8. exit
   9. Any failure during the create phase indicate a problem either with VSS or one of the writers which should be pursued with Microsoft.
7. Test open files options
   1. reset
   2. set verbose on
   3. set option differential
   4. set context volatile nowriters
   5. add volume c: (replace c: with the drive letter the snapshot is having problems.)
   6. create
   7. exit
8. Remove previously created VSS snapshots
   1. reset
   2. delete shadows all
   3. delete shadows volume c:
   4. delete shadows \\servername\share
   5. delete shadows oldest c:
   6. delete shadows exposed Z:
   7. delete shadows exposed
   8. exit
   9. NOTE: Use only one "delete" command out for the six "delete" commands versions.
9. Mount (Expose) a shadow copy to a drive, mountpoint, or share
   1. reset
   2. Expose | |
   3. exit
   4. EXAMPLE: expose {6aa67172-bec7-4688-94fc-4269c0032e85} c:\share
10. To dismount an exposed image run
    1. reset
    2. Unexpose | |
    3. exit
    4. or
    5. reset
    6. Unexpose
    7. exit
11. Run a diskshadow script
    1. DiskShadow allows scripting.
    2. Scripts consist out of diskshadow commands, written one per line in a text file. It is recommended to use the extension .dsh to differentiate scripts from regular text files but it is not necessary. For instance script.dsh is executed the same as script.txt if they feature the same content.
    3. WARNING -- the first line of the script MUST be a comment (prefixed with #) as the first script line may be skipped. It is good practice to end the script with a comment as well (i.e. #end script).
    4. DiskShadow can be run in scripted mode using the -s parameter, i.e.
    5. diskshadow -s c:\temp\script.txt
    6. Environment variables can be added
12. PowerShell
    1. DiskShadow one liners can be executed from an elevated PowerShell console, using the piping PowerShell capabilities. For instance, to list the VSS writers, type:
    2. "list-writers" | diskshadow
    3. NOTE: It is not possible to concatenate commands and run them in PowerShell.