ceph/systemd/ceph-mds.target

[Unit]
Description=ceph target allowing to start/stop all ceph-mds@.service instances at once
PartOf=ceph.target
Before=ceph.target
[Install]
WantedBy=multi-user.target ceph.target
fine-grained control systemd to start/stop/restart ceph services at once Signed-off-by: Zhi Zhang <zhangz.david@outlook.com> 2015-10-26 07:13:19 +00:00			`[Unit]`
			`Description=ceph target allowing to start/stop all ceph-mds@.service instances at once`
			`PartOf=ceph.target`
systemd: Add explicit Before=ceph.target The PartOf= and WantedBy= directives in the various systemd unit files and targets create the following logical hierarchy: - ceph.target - ceph-fuse.target - ceph-fuse@.service - ceph-mds.target - ceph-mds@.service - ceph-mgr.target - ceph-mgr@.service - ceph-mon.target - ceph-mon@.service - ceph-osd.target - ceph-osd@.service - ceph-radosgw.target - ceph-radosgw@.service - ceph-rbd-mirror.target - ceph-rbd-mirror@.service Additionally, the ceph-{fuse,mds,mon,osd,radosgw,rbd-mirror} targets have WantedBy=multi-user.target. This gives the following behaviour: - `systemctl {start,stop,restart}` of any target will restart all dependent services (e.g.: `systemctl restart ceph.target` will restart all services; `systemctl restart ceph-mon.target` will restart all the mons, and so forth). - `systemctl {enable,disable}` for the second level targets (ceph-mon.target etc.) will cause depenent services to come up on boot, or not (of course the individual services can be enabled or disabled as well - for a service to start on boot, both the service and its target must be enabled; disabling either will cause the service to be disabled). - `systemctl {enable,disable} ceph.target` has no effect on whether or not services come up at boot; if the second level targets and services are enabled, they'll start regardless of whether ceph.target is enabled. This is due to the second level targets all having WantedBy=multi-user.target. - The OSDs will always start regardless of ceph-osd.target (unless they are explicitly masked), thanks to udev magic. So far, so good. Except, several users have encountered services not starting with the following error: Failed to start ceph-osd@5.service: Transaction order is cyclic. See system logs for details. I've not been able to reproduce this myself in such a way as to cause OSDs to fail to start, but I have managed to get systemd into that same confused state, as follows: - Disable ceph.target, ceph-mon.target, ceph-osd.target, ceph-mon@$(hostname).service and all ceph-osd instances. - Re-enable all of the above. At this point, everything is fine, but if I then subseqently disable ceph.target, then try `systemctl restart ceph.target`, I get "Failed to restart ceph.target: Transaction order is cyclic. See system logs for details." Explicitly adding Before=ceph.target to each second level target prevents systemd from becoming confused in this situation. Signed-off-by: Tim Serong <tserong@suse.com> 2017-06-30 07:24:21 +00:00			`Before=ceph.target`
fine-grained control systemd to start/stop/restart ceph services at once Signed-off-by: Zhi Zhang <zhangz.david@outlook.com> 2015-10-26 07:13:19 +00:00			`[Install]`
			`WantedBy=multi-user.target ceph.target`