Log rotation periodically archives old log messages so that new messages are always written to a relatively small file.
日志循环会周期性地对旧日志进行归档，这样新消息就可以总能写到一个相对较小的文件中。
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Using a single combined log file makes it somewhat simpler to collect and scan data for anomalies when something happens, and to manage the growth and rotation of logs files.