November 2021
Intermediate to advanced
410 pages
12h 1m
Chinese
Content preview from MongoDB权威指南（第3版）
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部署
MongoDB
｜
379
24.5
系统管理
本节会介绍在进行部署之前应该注意的一些常见问题。
24.5.1
时钟同步
通常来说，各系统时钟的时间差在
1
秒之内最安全。副本集应该能够处理大部分时钟偏移
（
clock skew
）
。分片可以处理一部分偏移（如果超过几分钟，则日志中会出现警告），但最
好将其降低到最小。使时钟保持同步还可以更容易地从日志中了解发生了什么。
可以使用
Windows
系统中的
w32tm
工具和
Linux
系统中的
ntp
守护进程来保持时钟同步。
24.5.2
OOM killer
在极罕见的情况下，
MongoDB
会由于分配了过多的内存而成为
OOM killer
的目标。这种
情况通常发生在索引创建的过程中，因为这是
MongoDB
的常驻内存会对系统造成压力的
少数情况之一。
如果
MongoDB
进程
突然终止，并且日志中没有错误或退出消息，则应该检查
/var/log/
messages
（或任何内核中记录此类事件的地方），看看是否存在任何关于终止
mongod
进程
的消息。
如果内核因为内存的过度使用而关闭了
MongoDB
，那么应该会在内核的日志中看到如下
内容：
kernel: Killed process 2771 (mongod)
kernel: init invoked oom-killer: gfp_mask=0x201d2, order=0, oomkilladj=0
如果启用了日志（
journal
），那么此时只需重新启动
mongod
。如果没有启用日志，则需要
从备份中恢复或从副本重新同步数据。 ...
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