Comment 11 for bug 1703954

Here is an empty, encrypted volume prior to attachment:

-rw-rw----. 1 root qemu 4294967296 Jan 12 12:37 volume-14c92c19-5c3d-480e-8c19-c70c9304ebce

Then, during attachment, nova-compute does the following:

2018-01-12 12:39:36.357 215450 DEBUG oslo_concurrency.processutils [-] Running cmd (subprocess): ln --symbolic --force /dev/mapper/crypt-volume-14c92c19-5c3d-480e-8c19-c70c9304ebce /gpfs/fs_adapt2/openstack/cinder/volume-14c92c19-5c3d-480e-8c19-c70c9304ebce execute /usr/lib/python2.7/site-packages/oslo_concurrency/processutils.py:367

Results end up looking like:

lrwxrwxrwx. 1 root qemu 61 Jan 12 12:39 volume-14c92c19-5c3d-480e-8c19-c70c9304ebce -> /dev/mapper/crypt-volume-14c92c19-5c3d-480e-8c19-c70c9304ebce

Thus, after volume detachment, your /dev/mapper device is gone, and so is your volume and data