I frequently expand drives on my VMs. How can I rescan the drives without rebooting the server?
The easiest solution is to use scsitools script rescan-scsi-bus.
sudo apt-get install scsitools sudo rescan-scsi-bus
To do it without installing a utility on 14.04:
echo '1' > /sys/class/scsi_disk/0\:0\:0\:0/device/rescan
IMPORTANT: Be sure to replace the 0:0:0:0 with the appropriate disk for your purposes.