At last i started a tape restore and and then a IOmeter test from my Workstation with 4! Workers, i got a read speed of 107 MB/sec and have no problems with the restore speed.
I can start a IOmeter in a Virtual Machine with 4 Workers, they are reading with 95 MB/sec and the 4 Workers on the Workstation are running with 105 MB/sec at the same time....
And now? My hardware works...
I will test now with the Open-E again. But first i will load factory defaults, perhaps there are problems in the settings after the x updates...