In some cases, they can also be used to satisfy read requests to offload the primary shard.

在某些情况下，它们可以用来满足读取请求卸载主碎片。

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Replica shards are backup copies of all the data in the primary shard, and their main purpose is to recover from a primary shard failure to provide high availability.

复制碎片是主碎片中所有数据的备份副本，它们的主要目的是从主碎片失败中恢复，提供高可用性。

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For the primary shards, the surviving replica shard is promoted to a primary shard, and new replica shards are created on the other server by copying data from the newly promoted primary.

对于主碎片，存活的复制碎片将提升为主碎片，并在另一个服务器上创建新的复制碎片——从新提升的主碎片复制数据。

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