The mount point of the physical device attached to the instance while creation is different from the physical device attached inside the instance...
Instance Log:

but the disk attached to instance is different.when i try to run sudo fdisk -l in the instance

Is there anyway to pass the mountpoint of the device such as /dev/vdb in the command line using knife openstack server create...
the command which i used to bring up the server is
knife openstack server create --no-host-key-verify --node-ssl-verify-mode none --openstack-volumes --flavor --image --ssh-user <IMAGE_USER> -S --identity-file --network-ids --openstack-floating-ip --insecure --yes -VV --hint openstack -N <INSTANCE_NAME> --openstack-groups <SEC_GROUP> --run-list “" --environment