The reduction of servers and the implementation of clustering allowed maintenance to take place on the servers without requiring any downtime for the users.

服务器数量的减少和集群的实现允许在服务器上进行维护时，用户无需任何停机。

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It is advisable to execute this change during announced system downtime, unless you have the replica server running to take care of the unavailability of the server being upgraded.

建议在公告的系统停机时间执行这一修改，除非正在运行副本服务器，可以应对在升级期间服务器不可用的问题。

youdao

Step 2, the one which involved server downtime, was originally estimated to take around 2 hours based on the two servers being directly linked via gigabit ethernet.

第二步，最初预计停机时间是2小时，主要工作就是通过以太网把两台服务器连接起来。

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And if air travel is more your speed, why not take to the skies aboard this zero-emission Elektra airplane, which spends its downtime soaking up the suns rays in a solar hangar.

ENGADGET: Inhabitat's Week in Green: electric cars, solar planes, and really sweet lights