I just found this description from "get-help new-backup" in the SME PowerShell but still doesn't how I can avoid the LOG volume SnapShots
-BackupTruncatedLogs <Boolean ($True or $False)>
Short Form: bkTrcLogs
This option does a backup of the selected database logs including
those that will be truncated by a full backup type. When true this will
preserve up-to-the-minute restore capability for older backups. When false this
option can be used to conserve space on the LUN containing the backed up Exchange
transaction logs. For copy backup types, this will make a backup of the current
logs as well but they will not be truncated. The default is true.
Required? false
Position? False
Default value $True
Accept pipeline input? True
Accept wildcard characters? false