> For the complete documentation index, see [llms.txt](https://docs.verge.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.verge.io/run-the-platform/zh/cun-chu/preferred-tiers.md).

# 首选层

解释 VergeOS vSAN 中的首选层设置，它决定数据放置的首选存储层；当不可用时，会自动回退到其他层。

该 *首选层级* 该设置将为要使用的存储层建立一个“首选项”。如果该层不可用，或者该层空间不足，系统将自动切换到下一个更便宜（编号更高）的层；如果该层也不可用，则切换到再下一个更便宜的层。如果指定的首选层不可用，并且也没有更便宜的层可用，系统将切换到下一个更昂贵（编号更低）的层。

## 首选层示例

**下图显示了一个示例，其中已将第 4 层指定为首选层：**

![preferredtier.png](https://664309245-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FpODKGSQETqL1gSqyxIq3%2Fuploads%2Fgit-blob-7c3137ab402f03a48144e2d453a784f3ac1f4208%2Fpreferredtier.png?alt=media)


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