Hi [NAME],   In that case, you may need to remove the old RAID1 VD, as the RAID controller has it's configuration retain for previous RAID1 VD in the drive slots and when you tried to do a new VD, it may return an error. 
Hello, We have PowerEdge R510 with PERC H700 Raid controller. This server had 2 VDISK: RAID1 :   2 x 36 GB RAID6 :  12 x 2 TB   The RAID1 array died because we lost both disks. The RAID6 array is still good and visible in the Raid management interface. Now, we just want to replace the RAID1 array and reinstall the OS but we want to keep the RAID6 array absolutely untouched since it is good. We replaced the 2    36 GB disk and we can also see them in as unused disks in the management interface. We tried to create a new VDISK from these 2   36 GB disks (RAID1). We can select the disks and all other options but when we click on OK to go and create the VDISK, we get  a pop up telling that the creation has failed. Why is it failing ?Are we supposed to clear somehow the old RAID1 array before we can grate the new one ? Thank you   Gilbert
Perc H700 - Create new Virtual disk fails