因为我们在协议中没有数据库保证能提交或回滚(参阅步骤12)这一点，所以数据库可以不执行任何写人操作。
It might not perform any write operations, because we haven't gotten to the point in the protocol where the database guarantees being able to commit or rollback (see step 12).
将分割镜像初始化为快照时，将执行崩溃恢复，回滚所有未提交的事务，并使数据库可以被所有读或写操作访问。
The initialization of the split mirror as snapshot performs a crash recovery, rolls back all uncommitted transactions, and makes the database available for any read or write operation.
其中，三种常见的策略为：回写（writeback）、预定（ordered）和数据（data）。
Three of the most common strategies are writeback, ordered, and data.
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