Phase One :

If VSS snapshots are failing via ClusterLogics please check the following:
  • There is at least 5% of disk space available on system drive
  • the VSS plugin is installed
    To check this, look for Bacula VSS Plugin under Control Panel > Add/Remove Programs

If the above is OK you may need to re-register the VSS services and associated files via a batch file.
 
Open Notepad on the client server and paste the following:
 
cd /d %windir%\system32
net stop vss
net stop swprv
regsvr32 /s ole32.dll
regsvr32 /s oleaut32.dll
regsvr32 /s vss_ps.dll
vssvc /register
regsvr32 /s /i swprv.dll
regsvr32 /s /i eventcls.dll
regsvr32 /s es.dll
regsvr32 /s stdprov.dll
regsvr32 /s vssui.dll
regsvr32 /s msxml.dll
regsvr32 /s msxml3.dll
regsvr32 /s msxml4.dll
vssvc /register
net start swprv
net start vss
 
Save the above as vssregister.bat to the desktop of the client server.  Run the batch file by double-clicking.  This should run and then close upon success.  
Open a command prompt and type/paste the following:

vssadmin list providers
 
There should be at least one (typically Microsoft)

You can also download the batch file as attached to this article:

vssregister.bat

Run a backup to make sure everything runs correctly and the backup completes.
If you still have failures, look in event logs and make sure there is enough available unpaged RAM.

You may see an item like:
The shadow copy of volume C: could not be created due to insufficient non-paged memory pool for a bitmap structure.

You can also check if a VSS/snapshot will work on the server in question along with the drive in question by opening a command prompt and pasting the following where "D:" is the drive you want to check:

vssadmin create shadow /For=D:

Here is an example of drives C: and D: being successful :

 

Here is example of C: being good and D: failing:




Phase Two :

If re-registering the DLLs did not help and You're still receiving VSS Failure/Time-out , You will need to do more digging to identify the faulty vss writer, First Try to Run the .bat above and make sure all Writers are in Stable state

Before starting the next phase make sure you upgrade the following drivers : 

VOLSNAP.SYS

NTFS.SYS

SWPRV.DLL


1. Run Your Backup and allow the failure to happen 

2.Run "vssadmin list writers" and find the faulty writer , It should look similar to this : 

Writer name: 'Shadow Copy Optimization Writer'
   Writer Id: {4dc3bdd4-ab48-4d07-adb0-3bee2926fd7f}
   Writer Instance Id: {2cf36c73-92ed-4c38-a9f8-3855d3d362ca}
   State: [7] Failed
   Last error: Timed out

In this instance , It's the shadow copy optimizer that times out , Mostly each of the writers has it's own set specific registries , So more investigation will be required to have a better picture and isolate the issue , In this instance , Timeout value was added for sco writer in it's respective registries 

3. Run "VSSADMIN LIST PROVIDERS" to identify the vss provider on your machine , There might be more than one instance .

If you have other providers installed beside Microsoft , which could be StorageCraft provider, Symantec providers and Acronis Providers, you need to make sure that their files are also updated accordingly

4. Remove the following registry : 

HKLM/Software/Microsoft/EventSystem/{26c....../Subscriptions.

5. Reboot the machine to recovery mode and and force a full chkdsk (Open Command Prompt in Recovery and run chkdsk /f )

Keep in mind since VSS will cause more fragmentation during creation/expansion of restore points , There's a great possibility of conflict and disk errors .

Boot the machine normally and run your backups