VSSAdmin DNPublish

for System 
C:\>vssadmin list shadowstorage
vssadmin 1.1 - Volume Shadow Copy Service administrative command-line tool
(C) Copyright 2001-2005 Microsoft Corp.

Shadow Copy Storage association
  For volume: (C:)\\?\Volume{1f579c24-a50d-11dd-83df-xxxxxxxxxxxxx}\
  Shadow Copy Storage volume: (C:)\\?\Volume{1f579c24-a50d-11dd-83df-xxxxxxxxxxxxx}\
  Used Shadow Copy Storage space: 47.256 GB
  Allocated Shadow Copy Storage space: 49.405 GB
  Maximum Shadow Copy Storage space: 50 GB

c:\>vssadmin list shadows 
This will provide more information about what program is using the shadow storage

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For Exchange 
Issue: Backup is taking long time to complete or Inconsistent

1. Troubleshooting steps
vssadmin list writers

2. In Application Log, Related Event with Backup 
Event Id : 3156 

3. Increase the Diagnostic logging for "Exchange Writer"

Set-EventLogLevel "MSExchangeIS\9002 System\Exchange Writer" -Level Expert

To revert the Changes 

Set-EventLogLevel "MSExchangeIS\9002 System\Exchange Writer" -Level Lowest

and 
Set-EventLogLevel "MSExchangeIS\9002 System\Backup Restore" -level Expert
Set-EventLogLevel "MSExchange Repl\Service" -level Expert



4. Restart the "Microsoft Exchange Server Extension for Windows Server Backup" service