I found the solution. Formerly there was a RAID0 array from which I just removed the disks. In the raid controller bios this array still existed as an inactive one. Deleted this array and then I was able to create a new one.
Hi, We have a PE 2950 with SAS 6/iR integrated. We have a configured virtual disk of 2 73GB HDDs as RAID1. We bought two new Seagate Savvio 10K.6 ST900MM0006 900GB 10K 6Gbps 2.5" HDDs. I have tried to configure a virtual disk of these 2 new HDDs and at the end I receive "Create virtual disk failed". Neither RAID0 or RAID1 is to be created. For creation I use OpenManage Server Administrator  V7.1.0. What can be the cause of this problem?
SAS 6/iR "Create virtual disk failed"