SystemD and FIFO Sockets in RHEL7
There's a bug with a relevant discussion on systemd's approach to FIFO socket deletion. As of systemd-214 the issue with "stale" sockets was resolved by supplying the `RemoveOnStop` option to its corresponding `.service`. However, at the moment RHEL7 has systemd-208 as the default version; and I am seeing the following errors in `dmesg` output:
systemd: systemd 208 running in system mode. (+PAM +LIBWRAP +AUDIT +SELINUX +IMA +SYSVINIT +LIBCRYPTSETUP +GCRYPT +ACL +XZ) systemd: /usr/lib/systemd/system-generators/anaconda-generator exited with exit status 1. [ +0.056775] systemd: [/usr/lib/systemd/system/lvm2-lvmetad.socket:9] Unknown lvalue 'RemoveOnStop' in section 'Socket' [ +0.000675] systemd: [/usr/lib/systemd/system/dm-event.socket:10] Unknown lvalue 'RemoveOnStop' in section 'Socket'I'm not sure if LVM2 is referencing a feature that's not available in the default systemd version; AFAIK, my configuration is pretty much standard (default) regarding the pertinent components.
# rpm -qf /usr/lib/systemd/system/lvm2-lvmetad.socket lvm2-2.02.115-3.el7.x86_64 # yum info systemd Installed Packages Name : systemd Arch : x86_64 Version : 208 Release : 20.el7_1.2 Size : 11 M Repo : installed From repo : rhel-7-server-rpms # multipath -l Apr 24 03:48:25 | DM multipath kernel driver not loaded Apr 24 03:48:25 | /etc/multipath.conf does not exist, blacklisting all devices. Apr 24 03:48:25 | A default multipath.conf file is located at Apr 24 03:48:25 | /usr/share/doc/device-mapper-multipath-0.4.9/multipath.conf Apr 24 03:48:25 | You can run /sbin/mpathconf to create or modify /etc/multipath.conf Apr 24 03:48:25 | DM multipath kernel driver not loadedAccording to the bug report, RHEL 7.2 is planned to include systemd version 219 by default. This issue should be resolved then, if not sooner through a patch. Ultimately, this issue is not critical to the systems' operation.