cancel
Showing results for 
Search instead for 
Did you mean: 

FSDepends Registry Value and it's impact on Backup Exec's functionality

josh1432
Level 2

On Windows Server 2008 R2 Standard, I have been trying to create a VM through Hyper-V.

The following error

     "A Virtual Disk Provider for the specified file was not found"

was displayed, which has been addressed in the Support article below:

https://support.symantec.com/en_US/article.TECH124353.html

It suggests that the registry key "HKLM\SYSTEM\CurrentControlSet\Services\FsDepends" REG_DWORD value "Start" be changed from "3" to "0" as a solution.

It continues: "When any third-party backup software loads its tape device driver, the software can sometimes result in FSDepends.sys and VHDMP.sys not initializing correctly."

 

However, before I make the registry change and restart, could someone kindly please explain what the FSDepends.sys does and why Symantec Backup Exec requires the registry value to be set to a value of 3 in the first place? Was there an error in Backup Exec?

 

 

1 ACCEPTED SOLUTION

Accepted Solutions

VJware
Level 6
Employee Accredited Certified

Afaik, fsdepends.sys is a mini-filter driver and not directly called / used by Backup Exec. When BE loads its tape driver, it conflicts with fsdepends.sys being loaded as well. By setting the registry key to 0, it allows the fsdepends.sys to load immediately during boot up and thereby avoiding the conflict with the tape drivers. fsdepends.sys actually tracks file system dependencies and i believe either having a read at Windows Internals or checking with MS will provide more details.

Btw, it is originally a MS article and since it affects BE (and other backup software which supports tapes), it has been referenced on the other vendor sites. (I have posted an example link below) And as pkh suggested earlier, if you really would like more detail as to why fsdepends.sys does, then MS is indeed the appropriate place to ask.

Original MS issue - https://support.microsoft.com/en-us/kb/2013544

KB from Appasure which is similar to the BE's one - https://support.software.dell.com/appassure/kb/119790

 

View solution in original post

5 REPLIES 5

pkh
Moderator
Moderator
   VIP    Certified
If you read the MS KB which is referenced in the Symantec document carefully, the change is suggested by MS and not Symantec. If you are not comfortable with the suggested change then you should check with MS. Furthermore, failure to create a VM is not a BE problem, but a MS one. The value of 3 is not required by BE, but I suspect is the default value St by MS

josh1432
Level 2

Thank you pkh for responding to my request and partially answering my question.

If "the change is suggested by MS and not Symantec", it would seem strange that the support article on the Symantec Tech Support site I linked, which has the instructions listed under the heading in "Solution" was not suggested also by Symantec.
There is definitely a connection:

Symantec: "Hyper-V Virtual Machine(s) fails to start with the error "An error occurred while attempting to start the selected virtual machine(s)" after Backup Exec is installed on Windows 2008 R2 Host machines."
Microsoft: "When any third-party backup software loads its tape device driver, the software can sometimes result in FSDepends.sys and VHDMP.sys not initializing correctly."

However, that is besides the point.

I would actually much prefer an actual Symantec employee to explain what Symantec BE uses FSDepends.sys for.

Unfortunately, it doesn't really help that you can say the FSDepends setting of Manual (ie. 3) is not used without accompanying it with an explanation of what FSDepends does. All that would indicate is that you might not be as familiar with the issue as the actual Symantec employees who endorsed Microsoft's solution.

pkh
Moderator
Moderator
   VIP    Certified

Very simple.  BE has a problem and the problem is traced to the problem described in the MS KB, so the solution to the BE problem is that given in the MS KB.

1) FSDepends is part of Windows.  If you want to know what it does, you should ask MS.

2) BE might not be using FSDepends directly.  It could be using another function in Windows which in turns depends on FSDepends.

3) How is all these questions related to your stated problem of not being able to create a VM which is a MS problem and not a BE problem.

Note that this is a user-supported forum and nobody, including Symantec employees, are obligated to respond to your postings.

VJware
Level 6
Employee Accredited Certified

Afaik, fsdepends.sys is a mini-filter driver and not directly called / used by Backup Exec. When BE loads its tape driver, it conflicts with fsdepends.sys being loaded as well. By setting the registry key to 0, it allows the fsdepends.sys to load immediately during boot up and thereby avoiding the conflict with the tape drivers. fsdepends.sys actually tracks file system dependencies and i believe either having a read at Windows Internals or checking with MS will provide more details.

Btw, it is originally a MS article and since it affects BE (and other backup software which supports tapes), it has been referenced on the other vendor sites. (I have posted an example link below) And as pkh suggested earlier, if you really would like more detail as to why fsdepends.sys does, then MS is indeed the appropriate place to ask.

Original MS issue - https://support.microsoft.com/en-us/kb/2013544

KB from Appasure which is similar to the BE's one - https://support.software.dell.com/appassure/kb/119790

 

josh1432
Level 2

Thanks VJWare for the great reply :) this answers my question.