一、现象
主体，已断开

二、查看日志
主机查看错误日志D:\Program Files\Microsoft SQL Server\MSSQL10_50.MSSQLSERVER\MSSQL\Log\ERRORLOG
错误: 1474，严重性: 16，状态: 1。
Database mirroring connection error 4 '64(指定的网络名不再可用。)' for 'TCP://备机IP:5022'.
Database mirroring is inactive for database 'your_db_name'. This is an informational message only. No user action is required.
Error: 1474, Severity: 16, State: 1.
Database mirroring connection error 4 'An error occurred while receiving data: '121(信号灯超时时间已到)'.' for 'TCP://备机IP:5022'.
错误: 1479，严重性: 16，状态: 2。
The mirroring connection to "TCP://备机IP:5022" has timed out for database "your_db_name" after 10 seconds without a response.  Check the service and network connections.
错误: 1474，严重性: 16，状态: 1。

三、解决
第一，确保主备服务器5022端口可以连接，ping掉包不严重

第二，备机执行
ALTER ENDPOINT your_Endpoint_name STATE=STOPPED
GO
ALTER ENDPOINT your_Endpoint_name STATE=STARTED
GO

第三，主机执行

ALTER DATABASE your_db_name SET PARTNER RESUME

作者:ikmb@163.com