June 28, 2016 at 12:26 pm
Hi,
I am very much new to mirroring, I know how to set it up, but I don't know what to do when a principal server fails or the link between Principal and mirror server break.
We are using asynchronous mode., ie no automatic failover
I have read this (https://msdn.microsoft.com/en-us/library/dd207006.aspx) article regarding responding to failure of the principal
1. the first one says do nothing, leave the database unavailable until the principal becomes available again
My question is how will I know that the principal server will be available again, will it be in Recovery pending state or something?
2. the second one, if the principal database is lost but the principal server is still running, immediately attempt to backup the tail of the log on the principal database.
How can I take tail log backup when the principal database is lost?
Sorry if these questions sounds dumb
Thanks
June 28, 2016 at 3:29 pm
SQLAddict01 (6/28/2016)
Hi,I am very much new to mirroring, I know how to set it up, but I don't know what to do when a principal server fails or the link between Principal and mirror server break.
We are using asynchronous mode., ie no automatic failover
I have read this (https://msdn.microsoft.com/en-us/library/dd207006.aspx) article regarding responding to failure of the principal
1. the first one says do nothing, leave the database unavailable until the principal becomes available again
My question is how will I know that the principal server will be available again, will it be in Recovery pending state or something?
2. the second one, if the principal database is lost but the principal server is still running, immediately attempt to backup the tail of the log on the principal database.
How can I take tail log backup when the principal database is lost?
Sorry if these questions sounds dumb
Thanks
1) This is going to sound harsh, but it needs to be said bluntly: if you are responsible for this stuff then know that if it is part of the company's HA/DR plan then the company's very survival is at stake. A person/group responsible for this must absolutely know it inside and out in all modes of operation. Companies go out of business, or are sued out of business here in the US, when this stuff gets messed up.
2) How you respond to various failure modes depends on a BUNCH of things. There is no one right answer because what could be right for your scenario is patently wrong for someone else's.
3) As for backing up the tail of a log when the principal is lost, that could simply mean you do not have network connectivity to the primary machine with your application/web tier. That doesn't mean you can't backup the database log. There are other scenarios as well.
Best,
Kevin G. Boles
SQL Server Consultant
SQL MVP 2007-2012
TheSQLGuru on googles mail service
June 29, 2016 at 2:19 am
#1 As it is asynchronous with safety mode off, we need to manually force a failover, but this would likely result in possible data loss. Let's say we have 2 servers x, and y, assume x being primary, and y being secondary. Suppose x goes down, we do a force failover to y, and now say x comes back online, it would then automatically assume the role of mirror. However, the mirroring session would remain suspended, until you manually resume it.
#2 Please refere #2 by Kevin.
I hope this answers your question.
Thanks
Feivel
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