Having installed, but really not used sys-fs/lvm2 in about 4.1 branch kernel and >sys-apps/openrc-0.18 I've find error messages on start of some services.
# service lm_sensors start
* Caching service dependencies ...
File descriptor 3 (pipe:) leaked on lvm invocation. Parent PID 11855: /bin/sh
/run/lvm/lvmetad.socket: connect failed: Нет такого файла или каталога
WARNING: Failed to connect to lvmetad. Falling back to internal scanning. [ ok ]
The issue was known for a time ago.
For example — link to Debian bug-tracker — https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=466138
AFAIR it appears when CONFIG_BLK_DEV_DM is not set (as in my kernel was):
Device-mapper is a low level volume manager. It works by allowing
people to specify mappings for ranges of logical sectors. Various
mapping types are available, in addition people may write their own
modules containing custom mappings if they wish.
Probably sys-fs/lvm2 ebuild should perform check for this option and if failed — echo warning message in postinstall.