In SBS enviroments there is always problem with backup solutions that are afordable and reliable at the same time. HP has an excelent, quick and robust solution that you can easily implement in SBS environment. It’s called HP RDX and you can check HP website for more info – it is composed of internal or external device and hard disk based cartridge of different sizes. It allows you to copy at a speed between 20-35 MB/s or better around 100 GB / hour…
http://h10010.www1.hp.com/wwpc/us/en/sm/WF05a/12169-304616-3755725-3755725-3755725-3741006.html
http://www.youtube.com/watch?v=e5E1c0VrMyg
If you have virtualised SBS environment so you are running SBS 2008 or SBS 2011 on Hyper-V platform you can backup your SBS server by using iSCSI on Hyper-V host (you can try http://www.starwindsoftware.com/ with their fantastic iSCSI solution). When you have this software installed you can connect your RDX drive to your guest SBS server and use it to perform standard SBS backup on it.
This kind of solution will not work with Microsoft iSCSI target 3.3 (this is MS free iSCSI target that runs on Windows server 2008 R2) as it does not allow to use removable disks as source for iSCSI target disks (it only supports non-removable drives).