Seek for expert advise/solution for backup exe 12

Hi all,

Good day.

Currenty my place running a Symantec Backup Exe 12 on at Windows server 2003, this is a backup server for our place.

But the backup process is very slow and it take few week to run a full drive backup. We also using Tape Drive backup as well

Below is the data capacity need to be backup.

e: 515GB

i: 823gb

j: 1.49TB

k: 1.13TB

l: 175gb

m: 795gb

any solution to create a good and effective backup for all the data in each drive....

thanks.