请教下alwayson同步流程的疑问

Question

比如6个节点的alwayson，其中有一台机器的数据库状态不可用，变为RECOVERY_PENDING，这是主库还在正常备份日志，这时主库上的日志会截断吗，如果那台问题的辅库一直不处理，主库的日志是不是会越来越大？如果过了一天那台辅库的机器处理完毕，能够正常同步，同步的日志还是从主库上传来的吗

Answer 1

Yes for your questions.

Answer 2

Yes for your questions.

For example, six nodes alwayson ,One of the node status is RECOVERY_PENDING,now the primary database backup the log normally.My question is primary database log can be truncated? Will the logs get bigger and bigger?

Answer 3

if db log can be truncated. for long time later when Repair the error node ,why can also synchronize normally？ truncated<>clear?

Answer 4

Hi database_noob,

 

>>比如6个节点的alwayson，其中有一台机器的数据库状态不可用，变为RECOVERY_PENDING，这是主库还在正常备份日志，这时主库上的日志会截断吗，如果那台问题的辅库一直不处理，主库的日志是不是会越来越大？如果过了一天那台辅库的机器处理完毕，能够正常同步，同步的日志还是从主库上传来的吗

 

你的理解是正确的，如果辅助数据库的状态一直是recovery_pending,导致主要副本的日志发送不过去，日志就一直不会截断，即使是做了日志备份。主副本的日志会变得越来越大，所以建议先将有问题的辅助副本移除ag，处理好了在添加回去。

 

辅助副本处理好了，能正常同步了，日志还是会按照顺序从主要副本上传送过去。是有个flag标记在主要副本的日志中，表明从这开始的日志的记录还未发送到次要副本上。

 

Best regards,

Dedmon Dai

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Answer 5

tks explicit answer me

Answer 6

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