Symantec Backup Exec 2010 (Backup Speed Rate)

I use Symnatec Backup EXEC to take backup of my file server which is the size of 4 TB hard drive.

For past few I have been having problem with my Symantec Backup EXEC.

Its giving me the worst speed for backing up the files around 1000 MBPS but before it used to give 3000 MBPS. The backup Media type I use is LT05. File that are being backed up is only excel files.

Note : The Media is connected to the same device as where the software is installed

Server Config.

OS: Windows Server 2008 R2 Standard Edition SP1.

Processor : Xeon 1.8 GHZ

RAM : 32 (utilizing only 15 Gigs)

Hard Drive : 1 TB X 6 ( RAID 5)

Antivirus : Sophos Endpoint Client