Pease have a look at this TN: http://www.symantec.com/docs/TECH145791
It describes a condition where performance is slow when W2008 media servers are backing up themselves, but the information is worth having a look at. E.g:
1. The first is related to the Windows 2008 R2 kernel. Under heavy I/O the kernel may not perform as expected. The cause of this issue is documented in Microsoft KB article 982383, which says that a computer with heavy I/O may encounter decreased performance.
2. The second known cause of Netbackup 7 performance problems is related to the Power Options settings in Windows. By default, Windows sets the Power Options to Balanced, which attempts to balance the power consumption of the hardware, but may sacrafice performance. Performance improvements have been found when the Power Options setting is set to High performance. These settings can be found in Windows Control Panel, Control Panel\All Control Panel Items\Power Options.
3. A third known cause of Netbackup 7 performance problems is related to the TCP Chimney Offload and Recieve Side Scaling (RSS) settings of the network interface. In previous Technotes, such as 294308 and 29008 it was recommend to disable TCP Chimney Offload. For Windows 2008 R2 platforms, performance gains have been realized when TCP Chimney Offload is enabled. Microsoft article 912222 discusses TCP Chimney Offload and RSS and the purpose of each.
