Thanks intelliM for posting the clarification regarding the Windows VSS 10s time-out.
Just to add some context here - the post being referred in this thread is the following - http://sso.forum.commvault.com/forums/thread/49206.aspx
The VSS 10sec timeout is completely managed and enforced by Microsoft VSS framework and this is not a limitation imposed by backup vendors. This is to ensure that journalling is not overloaded by holding the writes for a very long period.
To create application-consistent snapshots, the writes need to be held while taking the HW snapshots and for this, Commvault's VSS Provider based agents (like Windows FileSystem, MS-SQL, Exchange and others) issues the backup request to the VSS framework which internally holds the writers and issues the request back to Commvault's VSS Provider to create the HW snapshots. These snapshots should be created within this 10sec window and needs the control to be returned back to VSS framework to release the writers - all within this 10sec window.
As far as I know, there is no override or any configuration to change this critical 10sec window.
If there are any queries, I will be more glad to clarify them to my best effort.