Errors that occur during an asynchronous write request , such as a disk failure during the i o request , occur on the thread pool thread and become visible upon a call to 异步写请求期间出现的错误（例如i / o请求期间的磁盘失败）在线程池线程上发生，并且在调用
Errors that occur during an asynchronous write request , such as a disk failure during the i o request , occur on the thread pool thread and throw exceptions when calling 异步写请求期间出现的错误（如i / o请求中期间出现的磁盘故障）发生在线程池线程上，并且在调用
For more information about being prepared for possible disk failure or other serious system problems , see " backups and other safeguards " earlier in this appendix 有关预防可能的磁盘故障或其他严重系统问题的详细信息，请参阅本附录前面的“备份和其他保护措施” ，也可参阅备份程序的帮助。
A database can be protected from the disk failures to a varying degree , depending on the resources and the application by setting up the system with any one of the following configurations 根据使用的资源和应用程序，通过下面的某一种配置设置系统可以使数据库在不同程度上免受磁盘故障的影响：
Failures in databases other than the mirrored database are not detectable in a database mirroring session . moreover , a data disk failure is unlikely to be detected , unless the database is restarted because of a data disk failure 由于网络会指示任何两个服务器实例之间的连接断开的时间，因此，数据库镜像会话中的每个服务器实例都会在另外一个服务器实例断开连接时立即受到警告。
This requires a lot more understanding and knowledge than just setting up raid - 1 on a test server or at home - specifically , you ll need to know exactly what raid - 1 will protect you against , and how to keep your raid volume up and running in case of a disk failure 与只是在测试服务器上或者在家中安装raid - 1相比，这要求您对raid有更深入的理解，并掌握更多的知识尤其是，您需要准确知道raid - 1可以提供哪些保护，并要了解万一出现磁盘故障，如何使raid卷保持在启动运行状态。
