Can you please check how you attach the volume to the instance: if the volume is attach with the path /dev/hd$ the volume will be visible only after a reboot. Please try to attach the volume like this: nova volume-attach <instance id=""> <volume id=""> /dev/vdc

I hope it'll resolve the issue.

grep mpt /sys/class/scsi_host/host?/proc_name

echo “- – -” > /sys/class/scsi_host/host#/scan

Run the first command. Should give u your host numbers to scan. Example host0 1 or 2. Run second one the rescan for new disks/volumes.

or do this command which will cover all hosts:

ls /sys/class/scsi_host/ | while read host ; do echo "- - -" > /sys/class/scsi_host/$host/scan ; done