The prepare_cinder_volume script used to attach Cinder volumes incorrectly detects /srv being used in /etc/fstab when the instance is also using NFS. The output is as follows:

Where would you like to mount it? </srv> 
Mountpoint /srv appears in /etc/fstab:

nfs-tools-project.svc.eqiad.wmnet:/srv/misc/shared/dumps/project        /mnt/nfs/labstore-secondary-project     nfs     vers=4,bg,intr,sec=sys,proto=tcp,noatime,lookupcache=all,nofsc,rw,hard  0       0


You will need to use a different mountpoint or edit /etc/fstab by hand before using this script.

The script should instead detect if /srv is used in the second column of /etc/fstab instead of just checking if the mountpoint exists in that line. The same issue arises as well, even if the line is commented out.