Troubleshooting/Testing VSS using DiskShadow on Windows 2008 By IBM

Problem(Abstract)

When diagnosing problems with SystemState backup or Open File Support/Online Image using VSS, it is sometimes useful to test the VSS portion by itself..

Resolving the problem

With Windows 2008, Microsoft included a tool called DiskShadow.exe that can be used to take snapshots of the system and much more. For the purpose of this technote, we will be limited to performing tests similar to what happens when Tivoli Storage Manager (TSM) performs a SystemState backup, Open File Support backup or an Online Image backup.

Obtain Writer Information:

When troubleshooting a problem, sometimes it is useful to obtain information about the writers, their status and the metadata.

You can start diskshadow and logging all outputs to a file by starting a Command Prompt and launching this command:
diskshadow /l c:\diskshadow.out

From the diskshadow prompt, issue the following commands:

reset
list writers
list writers status
list writers metadata
list writers detailed
list providers
exit

The output of all the above commands will be found in c:\diskshadow.out. 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.

Test a snapshot of SystemState

When dealing with SystemState backup failures, sometimes the problem is with TSM, sometimes on Windows either with VSS itself or with one of its writers. Testing outside TSM helps determine if the problem is within TSM or outside.

You can start diskshadow and logging all outputs to a file by starting a Command Prompt and launching this command:
diskshadow /l c:\diskshadowsys.out

From the diskshadow prompt, issue the following commands:

reset
set verbose on
set option differential
set context volatile
add volume c: (if the system is on more than one disk, specify them separated by a space)
create
exit

The output of all the above commands will be found in c:\diskshadowsys.out. Review this file for errors. Any failure during the create phase indicate a problem either with VSS or one of the writers which should be pursued with Microsoft.

Test a snapshot of a disk for Open File Support or Online Image with snapshot provider to VSS

When dealing with a problem doing an open file support backup or online image backup when VSS is used as the snapshot provider, it is sometimes useful to isolate if the problem is within or outside of TSM. This will perform a snapshot of the disk.

You can start diskshadow and logging all outputs to a file by starting a Command Prompt and launching this command:
diskshadow /l c:\diskshadowsnap.out

From the diskshadow prompt, issue the following commands:

reset
set verbose on
set option differential
set context volatile nowriters
add volume c: (replace c: with the drive letter the snapshot is having problems.)
create
exit

The output of all the above commands will be found in c:\diskshadowsnap.out. Review this file for errors. Any failure during the create phase indicate a problem either with VSS or possibly the disk.