E200i Controller interim recovery

I have an DL350 G5 with an E200i controller.

=> ctrl all show config

Smart Array E200i in Slot 0   (sn: QT7AMW1845     )

   array A (SAS, Unused Space: 0 MB)

      logicaldrive 1 (68.3 GB, RAID 1+0, Interim Recovery Mode)

      physicaldrive 1I:1:1 (port 1I:box 1:bay 1, SAS, 72 GB, OK)
      physicaldrive 1I:1:2 (port 1I:box 1:bay 2, SAS, 72 GB, Failed)

   array B (SAS, Unused Space: 0 MB)

      logicaldrive 2 (136.7 GB, RAID 5, OK)

      physicaldrive 1I:1:4 (port 1I:box 1:bay 4, SAS, 72 GB, OK)
      physicaldrive 2I:1:5 (port 2I:box 1:bay 5, SAS, 72 GB, OK)
      physicaldrive 2I:1:6 (port 2I:box 1:bay 6, SAS, 72 GB, OK)

   unassigned

      physicaldrive 2I:1:8 (port 2I:box 1:bay 8, SAS, 72 GB, OK)

As you can see one of the drives on array A is failed. I would like to define the unassigned drive as a hotspare. But for some unknown reason this ist not possible.

Thank you for your help.