Database Reference
In-Depth Information
Figure 31-6.
Asynchronous Database Mirroring
Database mirroring in High Performance mode does not affect the performance of the principal server,
although there is a possibility of data loss based on log records that are in the send queue at the time when the
principal server crashed.
Although both the principal and mirror server databases are byte-to-byte copies of each other, mirroring does
not update the data files at the time when it hardens the log records in the transaction log. SQL Server applies
the changes to the data files on the mirror server by replaying the log records asynchronously, regardless of the
database-mirroring mode.
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synchronous database mirroring only guarantees that log records are hardened in the transaction log
synchronously. it does not guarantee nor provide synchronous changes of the data files.
Caution
