Comment 4 for bug 1153842

By digging further into this issue, we found out that there's a bug in Hyper-V related to the way the SCSI volumes are queried. If LUN0 is not queried (attached in the case of Nova), other volumes are not properly becoming available in the guest.

In practice, you cannot attach a volume to /dev/sdc if a volume hasn't been attached to /dev/sdb before (/dev/sda is the root volume / local disk connected to the IDE channel).

Here's a Linux Kernel patch that works around this issue, although it didn't merge yet:
http://www.spinics.net/lists/linux-scsi/msg65056.html