rngd.service 启动失败的处理

[root@localhost ~]# systemctl --failed
  UNIT              LOAD   ACTIVE SUB    DESCRIPTION
● mdmonitor.service loaded failed failed Software RAID monitoring and management
● postfix.service   loaded failed failed Postfix Mail Transport Agent
● rngd.service      loaded failed failed Hardware RNG Entropy Gatherer Daemon

LOAD   = Reflects whether the unit definition was properly loaded.
ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
SUB    = The low-level unit activation state, values depend on unit type.

3 loaded units listed. Pass --all to see loaded but inactive units, too.
To show all installed unit files use 'systemctl list-unit-files'.
[root@localhost ~]# ^C
[root@localhost ~]# systemctl status rngd
● rngd.service - Hardware RNG Entropy Gatherer Daemon
   Loaded: loaded (/usr/lib/systemd/system/rngd.service; enabled; vendor preset: enabled)
   Active: failed (Result: exit-code) since 四 2016-11-10 13:59:29 CST; 41min ago
 Main PID: 2116 (code=exited, status=1/FAILURE)

11月 10 13:59:29 localhost.localdomain systemd[1]: Started Hardware RNG Entropy Gatherer Daemon.
11月 10 13:59:29 localhost.localdomain systemd[1]: Starting Hardware RNG Entropy Gatherer Daemon...
11月 10 13:59:29 localhost.localdomain rngd[2116]: Unable to open file: /dev/tpm0
11月 10 13:59:29 localhost.localdomain rngd[2116]: can't open any entropy source
11月 10 13:59:29 localhost.localdomain rngd[2116]: Maybe RNG device modules are not loaded
11月 10 13:59:29 localhost.localdomain systemd[1]: rngd.service: main process exited, code=exited, status=1/FAILURE
11月 10 13:59:29 localhost.localdomain systemd[1]: Unit rngd.service entered failed state.
11月 10 13:59:29 localhost.localdomain systemd[1]: rngd.service failed.

【解决：修改此服务的启动状态】

cp /usr/lib/systemd/system/rngd.service /etc/systemd/system

vim /etc/systemd/system/rngd.service 

[Unit]
Description=Hardware RNG Entropy Gatherer Daemon

[Service]
ExecStart=/sbin/rngd -f

[Install]
WantedBy=multi-user.target

  systemctl daemon-reload

 systemctl restart rngd

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【参考：】

[彻底找到 Tomcat 启动速度慢的元凶] http://www.tuicool.com/articles/uaiURzF

在这篇文章中，指出rndg服务是生成随机数的熵服务，配置不当可能阻塞i进程造成tomcat慢等问题；