Then on the VD MGMT screen, highlight the controller in the upper-left, F2, Foreign, Import. It should move one from foreign to online and leave the other as failed ... leave things as is until you can confirm the OS boots and is ok, then you can rebuild the remaining disk.
I have a PE2900 with a PERC 5i, The first volume is a RAID 5 with three disks.  This morning the PERC controller says that two of the disks (MAXTOR SAS 68GB 10K RPM) are missing. Is that normal to lose two disks at the exact same time?  Or could it be the controller that's going bad? Is there anyway to test these drives without breaking the Virtual Disk?  Or am I out of luck losing two out of three disks in an RAID 5?
PERC 5i - RAID 5 with 3 Disks shows 2 Disks missing?