Within SBS 2011 you can create a backup to an external disk. USB or equal. Now i figured out earlier that you can trick SBS 2011 to write the backup to an remote destination.
And you can restore backups if you use a script that makes folders by the day.
Now I figured out you could create a backup to an ISCSI target. To do this you have to go first to a remote storage device which support iSCSI. In my case I used an Readynas Pro4.
You’ve to go to volumes > volume-settings > iSCSI > enable support for iSCSI > create a new LUN with the size you want [ I
choose 1024MB or 1GB ]
After you created a new iSCSI lun on the storage device you go to the iSCSI initiator
You will get a warning > click on Yes
Find the target ip address and click on Quick Connect. When you’ve done this the name will pop up in the Discovered Targets.
In the Windows disk management you’ve to create a new disk. After you’ve done this you have to go to the SBS 2011 console.
check “configure serverbackup”
Lets get started > click on next.
Specify the backup destination.
Check the box infront of Show all valid internal and external backup destinations.
There will show up a new Disk  with a name and size. Click on Next to continue.
Give the backup disk a label and click on Next to continue.
Select all drives as you could see the iSCSI target isn’t present in this view. Click on Next to continue.
Configure the schedule of the backup. This is a personal choice to configure.
check if all settings are correct. When these are correct you could configure the backup. By clicking on Configure.
Confirm that the backup destination could be formatted. [ click on
The backup will now be configured.
The backup is now configured now you could test in the SBS 2011 console if the backup works. [ in my case it worked and went smoothly ]