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Help, my database is corrupt. Now what?


Help, my database is corrupt. Now what?

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Jeff Moden
Jeff Moden
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Awesome article, Gail. Wish I had it when MSDB went sour on one of my Dev servers especially since my predecessors saw no need to backup a Dev Server. How much of this applies to the system's databases (not including TempDB, of course)? And, pardon my ignorance on the subject... I'm more of an Application DBA than a System's DBA.

--Jeff Moden

RBAR is pronounced ree-bar and is a Modenism for Row-By-Agonizing-Row.
First step towards the paradigm shift of writing Set Based code:
Stop thinking about what you want to do to a row... think, instead, of what you want to do to a column.
If you think its expensive to hire a professional to do the job, wait until you hire an amateur. -- Red Adair

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SDM
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At the risk of being redundant, excellent article, Gail. It should be compulsory "calm down and think" reading for any DBA facing an apparent catastrophe. Bookmarked and link mailed to collegues.

Stephen



Ol'SureHand
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SDM (2/16/2009)
At the risk of being redundant, excellent article, Gail. It should be compulsory "calm down and think" reading for any DBA facing an apparent catastrophe. ..
Stephen

Same from me - there should be a prize for you, and not just for this article. This is so helpful to all accidental DBA's ... it's not funny!
Montana Life
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Great article. Thanks for taking the time to create it. An excellent resource for sure.

Mike

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GilaMonster
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Jeff Moden (2/16/2009)
How much of this applies to the system's databases (not including TempDB, of course)?


MSDB can be repaired, I believe (haven't tried it). Master I would recommend restore or rebuild, though I have seen someone repair it successfully. Model, since it should have nothing in it, you should be able to copy from another server.

Depends what the corruption is. If it's just in the nonclusters, then repair's probably safe even in the system databases. If it's in the clustered index then my recommendation would be restore or rebuild (especially with master)

Master and msdb can be completely recreated, by the rebuild master function of the installer (master) or by script (msdb). It won't get any data back, but it will get the DB usable and free of corruption.

Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

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Ninja's_RGR'us
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GilaMonster (2/17/2009)
Jeff Moden (2/16/2009)
How much of this applies to the system's databases (not including TempDB, of course)?


MSDB can be repaired, I believe (haven't tried it). Master I would recommend restore or rebuild, though I have seen someone repair it successfully. Model, since it should have nothing in it, you should be able to copy from another server.

Depends what the corruption is. If it's just in the nonclusters, then repair's probably safe even in the system databases. If it's in the clustered index then my recommendation would be restore or rebuild (especially with master)

Master and msdb can be completely recreated, by the rebuild master function of the installer (master) or by script (msdb). It won't get any data back, but it will get the DB usable and free of corruption.



That begs this question... assuming you have a corrupt backup of msdb, can you rebuild it then reimport the data back in?
Jack Corbett
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GilaMonster (2/17/2009)
Jeff Moden (2/16/2009)
How much of this applies to the system's databases (not including TempDB, of course)?


MSDB can be repaired, I believe (haven't tried it). Master I would recommend restore or rebuild, though I have seen someone repair it successfully. Model, since it should have nothing in it, you should be able to copy from another server.

Depends what the corruption is. If it's just in the nonclusters, then repair's probably safe even in the system databases. If it's in the clustered index then my recommendation would be restore or rebuild (especially with master)

Master and msdb can be completely recreated, by the rebuild master function of the installer (master) or by script (msdb). It won't get any data back, but it will get the DB usable and free of corruption.


I had to deal with a suspect msdb (SQL 2000) with no backups, so I had to recreate it. This was one of those departmental installs of SQL Server that I was not involved with until it crashed. There were some good articles on MSDN on how to do it.



Jack Corbett
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Check out these links on how to get faster and more accurate answers:
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webrunner
webrunner
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Thanks for the article. As you said, I hope I will never need it - though just last week I saw the first, trivial, error that I repaired with the DBCC UPDATEUSAGE command, before you had posted your article. That was scary enough that I read your entire article when I saw the title, and I immediately added it to my briefcase as soon as I was done.

This is a great service to the community. Thanks again!

webrunner

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Ref.: http://tkyte.blogspot.com/2009/02/sql-joke.html
JJ B
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This article was well written. I appreciate the time you took to lay it all out in a logical manner and to explain the different scenarios. Most helpful. Thanks.
Anipaul
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Great article. Fantastic way of writing....



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