First, snapshots. Any backup operation (even an incremental backup, probably) is going to take a significant amount of time to complete. Unless you can lock your store while the backup is taking place, you will probably have a problem with inconsistent data. I suggest you investigate your fs and system possibilities for taking snapshots. You lock the store, take the snapshot (which should be very, very quick) and unlock the store. Your snapshot now contains a consistent replica of your store which can be backed at any pace you need. Look for volume shadow copies in Windows land, LVM snapshots in Linux, etc.
Second, replication. Again, any backup job is probably going to take a decent chunk of IO and CPU performance away from the store. Either your main app's performance will be affected or your backup will take ages to complete. If you can keep your storage system continuously replicated to a second system, you'll be able to back up without worries of affecting your live, production system. This replica might also be useful to prevent downtime (if the main storage fails, switch to the replica). When using replication, you take the snapshots in the replicated system- needing only to pause the replication while the backup is taken.
Third, once you have replication and snapshots, you just need to find a backup method which makes sense wrt. to bandwidth, storage and your requirements. First of all, figure out how back you want to go when recovering. Do you only need a copy of your storage as it was yesterday? 8 hours ago? Do you need to go back and recover files from last week? Last month? Last year?
How long does a full copy of your storage take? How long does a copy of a daily increment take? This limits how often can you take full backups and incremental backups. If you are not deleting data from your store, a replica might be enough.
Last, if you are moving huge volumes of data, you are probably using a SAN. And have a service contract. Your SAN probably has something builtin to handle backups, or at least the guys that support it should give you more specific ideas...