Comment 41 for bug 1373513

Turns out this can be addressed by making our filter a global_filter in lvm.conf.

The issue that we're running into is that dev files can come and go on the system, and there are cases where an LVS or VGS call will try and open a dev/sdX device that no longer exists when trying to query it for LVM data to see if it's an LVM disk. I added a filter a while back via /etc/cinder/lvm.conf, but it turns out that doesn't do us any good for the device open/query routines on lvs and vgs. For those you need to use the global_filter which tells LVM to not even bother with devices other than those specified by said filter.

There's also a possibility that we can just skip the filters and use lvmetad which is not enabled by default on Ubuntu. Afazekas mentioned something about this earlier today but I wasn't sure what he was referring to until I read some man pages and it turns out that does a lot of the same things as filters only a bit smarter and more dynamically. I would like some investigation done with that approach though because it also changes the activate/deactivate behavior so I want to make sure we fully understand it and test it thoroughly before adding it.