To work around the issue, install Acronis Agent on the Windows SBS machine locally

How to manually uninstall Acronis True Image 9.x and Echo series from Windows systems

Backup Exec from Symantec takes exclusive control over tape drive, and no other software, including Windows NT Backup, can access it

By default, MS SharePoint on Windows SBS does not have any MS SQL user with the sysadmin role.

You need to assign the sysadmin role for proper Acronis SharePoint operation.

Take the following steps to give any Windows user an MS SQL sysadmin role:

List of Acronis products that support Windows Small Business Server 2011