Ceph 时钟偏移问题 clock skew detected 解决方案--- 部署内网NTP服务

告警：HEALTH_WARN clock skew detected on mon.ip-10-25-195-6; 8 requests are blocked > 32 sec; Monitor clock skew detected

原因：

MON可能被MON节点之间的重要的时钟偏移激烈的影响。这经常会转变为没有明显原因的诡异的行为。为了避免这种问题，你应该在MON节点上运行一个时间同步的工具。

默认最大容忍的时钟偏移为0.05s，不建议修改这个官方开发推荐值。私自未经测试修改虽然无数据丢失风险，可能会对MON集群和总体集群健康导致意外的作用。

如果你遇到这个告警，同步时钟，在MON上运行NTP的客户端会有帮助。如果经常遇到这个问题，可能是因为使用了远端的NTP服务器，请考虑在内网部署NTP服务器。

在MON/OSD/RGW节点部署NTP服务的操作步骤：

1. apt-get install ntp
2. 修改ntp配置 /etc/ntp.conf
3. 重启ntp服务

/etc/ntp.conf

# /etc/ntp.conf, configuration for ntpd; see ntp.conf(5) for help
#sync time interval
tinker step 0.5 

driftfile /var/lib/ntp/ntp.drift

# Enable this if you want statistics to be logged.
#statsdir /var/log/ntpstats/

statistics loopstats peerstats clockstats
filegen loopstats file loopstats type day enable
filegen peerstats file peerstats type day enable
filegen clockstats file clockstats type day enable

# Specify one or more NTP servers.

# Use servers from the NTP Pool Project. Approved by Ubuntu Technical Board
# on 2011-02-08 (LP: #104525). See http://www.pool.ntp.org/join.html for
# YY NTP servers
server 121.14.36.27   iburst
server 221.228.209.14 iburst
server 183.57.81.221  iburst
server 113.142.33.209 iburst
server 106.38.198.9   iburst

# Use Ubuntu‘s ntp server as a fallback.
#pool ntp.ubuntu.com

# Access control configuration; see /usr/share/doc/ntp-doc/html/accopt.html for
# details.  The web page <http://support.ntp.org/bin/view/Support/AccessRestrictions>
# might also be helpful.
#
# Note that "restrict" applies to both servers and clients, so a configuration
# that might be intended to block requests from certain clients could also end
# up blocking replies from your own upst