Wow – today is all about new content. As if I haven't already blogged about enough stuff to keep you reading through next week, the February issue of TechNet Magazine is now available and contains a feature article I wrote about understanding how logging and recovery work inside SQL Server.
The article covers:
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What is logging?
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What is recovery?
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The transaction log (include logical and physical architecture)
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Recovery models and how they affect the behavior of the transaction log
There's also a ten-minute screencast video where I demonstrate a runaway transaction log.
Check it out at http://technet.microsoft.com/en-us/magazine/2009.02.logging.aspx.
7 thoughts on “TechNet Magazine: feature article on understanding logging and recovery”
Hello Paul,
I get to know you from a Spanish Microsoft technical support advisor who mentioned you in a conference during a SUMMIT organized by http://www.solidq.com in Madrid (Spain).
I would like to thank you greatly this article because I believe that without it I would not ever be able to understand what’s going on with my transaction log growth. Before reading it a have tried hard with the help of SQL without success.
But can I be named”involuntary DBA”? I think whoever has the patience to understand an article as dense in concepts as this one must be at least a person who is actively seeking to be DBA.
I recommend every one reading it and I don’t understand why this is the first comment for this post.
Hi Paul,
Is logging disabled in EMERGENCY mode?
Yes – in emergency mode the database is read only except for running DBCC CHECKDB with the emergency-mode repair option I built for 2005.
Does DBCC CHECKDB generate log records?
Yes. You can put repair in a transaction and roll it back. EXCEPT not for emergency-mode repair or if using the undocumented REPAIR_ALL option to rebuild GAM or SGAM pages. Those are both irreversible operations.
Thanks Paul. I am bit confused here. So, does DBCC CHECKDB get mirrored to secondary replica?
You can’t put a database in single-user mode if it’s part of an AG. So no. You’d need to remove, repair, re-add.