在主存储上使用重复数据删除也会有成效，但却不要期望可以达到像备份实施时典型的2.5倍到3倍的比例这样高的数据压缩比。

There are some gains to be had here, but don't expect the same data reduction ratios that you'll see in backup operations; 2.5X to 3X is typical.

youdao

每当数据库的模式发生更改，或者进行像添加或删除数据文件、添加或删除表空间这样的更改时，建议管理员执行脱机备份。

Administrators are advised to do an offline backup whenever the schema of the database changes, or changes are made such as adding or removing data files, and adding or removing of table Spaces.

youdao

例如，如果要把多个目录复制到备份目录，就会像清单2这样做。

For example, if you are copying multiple directories to a backup directory, Listing 2 will do what you want.

youdao

Almost--the best analogy here is backing up a computer.

最形象地说，这就像给电脑备份。

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