#### ceph软件包升级完成，执行命令重启服务
sudo systemctl restart ceph-mds@"$HOSTNAME"
#### 故障现象
服务可以启动，启动后显示有报错信息：
Nov 23 17:14:45 ceph-6-12 systemd[1]: [/usr/lib/systemd/system/ceph-mds@.service:18] Unknown lvalue ‘TasksMax‘ in section ‘Service‘
详细如下：
[ptmind@ceph-6-12 ~]$ sudo systemctl status ceph-mds@"$HOSTNAME"
```
● ceph-mds@ceph-6-12.service - Ceph metadata server daemon
Loaded: loaded (/usr/lib/systemd/system/ceph-mds@.service; enabled; vendor preset: disabled)
Active: active (running) since Wed 2016-11-23 17:14:45 CST; 57s ago
Main PID: 538956 (ceph-mds)
CGroup: /system.slice/system-ceph\x2dmds.slice/ceph-mds@ceph-6-12.service
└─538956 /usr/bin/ceph-mds -f --cluster ceph --id ceph-6-12 --setuser ceph --setgroup ceph
Nov 23 17:14:45 ceph-6-12 systemd[1]: Started Ceph metadata server daemon.
Nov 23 17:14:45 ceph-6-12 systemd[1]: Starting Ceph metadata server daemon...
Nov 23 17:14:45 ceph-6-12 ceph-mds[538956]: starting mds.ceph-6-12 at :/0
Nov 23 17:14:45 ceph-6-12 systemd[1]: [/usr/lib/systemd/system/ceph-mds@.service:18] Unknown lvalue ‘TasksMax‘ in section ‘Service‘
Nov 23 17:14:45 ceph-6-12 systemd[1]: [/usr/lib/systemd/system/ceph-mds@.service:18] Unknown lvalue ‘TasksMax‘ in section ‘Service‘
Nov 23 17:14:45 ceph-6-12 systemd[1]: [/usr/lib/systemd/system/ceph-mds@.service:18] Unknown lvalue ‘TasksMax‘ in section ‘Service‘
Nov 23 17:14:46 ceph-6-12 systemd[1]: [/usr/lib/systemd/system/ceph-mds@.service:18] Unknown lvalue ‘TasksMax‘ in section ‘Service‘
Nov 23 17:14:46 ceph-6-12 systemd[1]: [/usr/lib/systemd/system/ceph-mds@.service:18] Unknown lvalue ‘TasksMax‘ in section ‘Service‘
Nov 23 17:14:53 ceph-6-12 systemd[1]: Started Ceph metadata server daemon.
```
#### 查询相关文档：
http://tracker.ceph.com/issues/15560
http://tracker.ceph.com/issues/15581
文档都说是个bug ，又碰到一个bug ，汗。。。。。。。。。。
根据文档提示信息排查解决，发现这个问题只要安装或升级systemd基础库相关软件包，就能解决，所以果断安装升级systemd。
sudo yum install systemd-*
#### 然后重启服务：
sudo systemctl restart ceph-mds@"$HOSTNAME"
再查查看服务状态：
[ptmind@ceph-6-12 ~]$ sudo systemctl status ceph-mds@"$HOSTNAME"
```
● ceph-mds@ceph-6-12.service - Ceph metadata server daemon
Loaded: loaded (/usr/lib/systemd/system/ceph-mds@.service; enabled; vendor preset: disabled)
Active: active (running) since Wed 2016-11-23 17:59:51 CST; 8s ago
Main PID: 666298 (ceph-mds)
CGroup: /system.slice/system-ceph\x2dmds.slice/ceph-mds@ceph-6-12.service
└─666298 /usr/bin/ceph-mds -f --cluster ceph --id ceph-6-12 --setuser ceph --setgroup ceph
Nov 23 17:59:51 ceph-6-12 systemd[1]: Started Ceph metadata server daemon.
Nov 23 17:59:51 ceph-6-12 systemd[1]: Starting Ceph metadata server daemon...
Nov 23 17:59:51 ceph-6-12 ceph-mds[666298]: starting mds.ceph-6-12 at :/0
```
报错信息不再提示；
本文出自 “康建华” 博客，谢绝转载！
ceph升级到10.2.3 版本启动服务报错：Unknown lvalue 'TasksMax' in section 'Service'
原文：http://michaelkang.blog.51cto.com/1553154/1875953