problem with backup sharepoint sql DB

hi

using backup exec 2010 R3 SP4 to backup sharepoint sql server , server is 2003 R2 64bit

sometimes the backup fails and i get this well knowen error ID 25 VOLSNAP on the server "The shadow copies of volume D: were deleted because the shadow copy storage could not grow in time. Consider reducing the IO load on the system or choose a shadow copy storage volume that is not being shadow copied."

now i read many solutions on the web including moving the VSS Shadow copy to another disk and changing the MinDiffAreaFileSize in the registry

both not help too much

any good solution for that problem ?