Block Level File Backup - any thoughts / experience?

  • 12 October 2021
  • 3 replies

Userlevel 4
Badge +12

I have servers with 10’s of Millions of general user files (.DOC, .XLS) files that are ‘manageable’ using the Standard File Agent method of backup


I’ve often considered the Block Level method, but its the idea of ‘another Filter’ Driver in the Windows stack that concerns me:

  1. Not due to the quality of the code coming out of CommVault (which is very high)
  2. But due to the nature of Anti-Virus drivers, and their updates that often disrupt other filter drivers - with the small potential for a blue screen


I’d be interested in any thoughts, comments, experience

(The Windows Servers hosting the File Servers are 2016 and 2019 NTFS)


Many Thanks

3 replies

Userlevel 4
Badge +8

Hello @YYZ

From our experience from the support end, as long as the AV Exclusions are put into place on said server, there should be no issue.

From the sound of it, it is a physical server which would require the Configuration of Block-Level Backups ( with the Windows File System agent.

BUT if it is a VM, you can also back it up through the Virtual Server Agent, which takes the windows filter drivers out of the equation.


Other than that, as long as AV exclusions are in place than there shouldn’t be anything to be concerned about!

Userlevel 7
Badge +21

I’ve not seen AV interfere much with the block level drivers, they mainly disrupt archive recalls from the cvhsm driver - but that is due to the nature of the operations and commvault needing to intercept the I/O.

I believe VSS is primarily used in the snap/capture of the data, whereas the block level driver is more for tracking changes for incremental backups.

I think you should be good, although always helpful to follow what @Dan White mentioned and put the right exclusions in place.

Userlevel 4
Badge +12

Hi @Dan White 

Its a VM - but a key requirement is fast recovery of individual files and the ability to ‘search’ for those file across date ranges, file types etc; esepcially where the user cant remeber the date range when the missing file disappeared


When you say AV exclusions - which ‘folders’ would those exclusions apply to? - Do you mean

  • the End User Data Volumes//Drives/Folders
  • or would it be the above - but only during the period the backup is taking place?
  • or something else?


Hi @Damian Andre 

You almost read my mind:

I was think of the CVHSM driver!! -

Had a bad experience, and no amount of explanation to the customer that

a) the commvault archive driver is ‘good’, but

  1. the AV driver is being updated regularly and is essentially behaving badly.

Understand what you mean that for “Block File” the driver might be more of a ‘passive reader’, as opposed to the Archive Driver which was ‘reading, and intercepting’ traffic to modify what was being recalled.