As a non-LTS release, 15.10 has a 9-month month support cycle and, as
such, the support period is now nearing its end and Ubuntu 15.10 will
reach end of life on Thursday, July 28th. At that time, Ubuntu Security
Notices will no longer include information or updated packages for
Ubuntu 15.10.
**
This problem went away when I added udev_log=debug to
/etc/udev/udev.conf and ran update-initramfs -u. (Aside: someone more
knowledgeable please update the advice on
https://wiki.ubuntu.com/DebuggingLvm.)
Here is an almost-minimal sequence:
1) do a fresh install.
2) reboot into the new system.
