June 19, 2008 at 3:17 am
I am having these errors while I run DBCC CHECKDB ( myDB )
Msg 8966, Level 16, State 2, Line 1
Unable to read and latch page (1:2542368) with latch type SH. 23(Data error (cyclic redundancy check).) failed.
Msg 8964, Level 16, State 1, Line 1
Table error: Object ID 2020202247, index ID 1, partition ID 72057594145669120, alloc unit ID 72057594087800832 (type LOB data). The off-row data node at page (1:2444050), slot 0, text ID 901891555328 is not referenced.
I have already executed dbcc dbreindex(myTable) successfully, but I'm still having errors.
please comment.
June 19, 2008 at 7:18 am
Check these out. Paul is the best when discussing corruption. It's definitely not the best scenario for you but may at least get you started.
http://www.sqlteam.com/forums/topic.asp?TOPIC_ID=104090
http://www.eggheadcafe.com/forumarchives/SQLServerserver/Jul2005/post23536458.asp
-- You can't be late until you show up.
June 19, 2008 at 7:34 am
Do you have a backup of that database?
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
June 19, 2008 at 8:40 am
unfortunately i don't have backup.
June 19, 2008 at 8:53 am
Check out Paul Randals Excellento Work here: http://blogs.msdn.com/sqlserverstorageengine/archive/tags/DBCC+CHECKDB+Series/default.aspx
and http://www.sqlskills.com/blogs/paul/
Maninder
www.dbanation.com
June 19, 2008 at 7:06 pm
Looks like you have a corrupt page (and CRC indicates hardware problems) in a leaf-level page of the clustered index of your table. The data on the page has been lost. The LOB error is because a row on that page pointed to the LOB value - as the row has been lost, and so could not be processed by CHECKDB, the LOB value is effectively orphaned.
If you don't have a backup, the only way to get around this is to run REPAIR_ALLOW_DATA_LOSS (which is what CHECKDB will have recommended). This will delete the clustered index leaf-level page, and all the LOB values that are referenced by rows on that page. It will also cause any non-clustered indexes on that page to be rebuilt. Manually rebuilding the clustered index cannot fix the problem.
So - you need to run repair. You can determine the range of key values that are going to be deleted using the method in my recent blog post (see http://www.sqlskills.com/blogs/paul/2008/06/09/CHECKDBFromEveryAngleUsingDBCCPAGEToFindWhatRepairWillDelete.aspx).
And then do root-cause analysis to determine why the corruption occured in the first place (look in error logs, turn on page checksums, run SQLIOSim) and get a backup strategy to prevent future data loss!
Hope this helps
Paul Randal
CEO, SQLskills.com: Check out SQLskills online training!
Blog:www.SQLskills.com/blogs/paul Twitter: @PaulRandal
SQL MVP, Microsoft RD, Contributing Editor of TechNet Magazine
Author of DBCC CHECKDB/repair (and other Storage Engine) code of SQL Server 2005
June 19, 2008 at 7:08 pm
Btw - before running repair you should always take a backup - just in case something goes wrong - you'll at least have the corrupt database to fall back on.
Paul Randal
CEO, SQLskills.com: Check out SQLskills online training!
Blog:www.SQLskills.com/blogs/paul Twitter: @PaulRandal
SQL MVP, Microsoft RD, Contributing Editor of TechNet Magazine
Author of DBCC CHECKDB/repair (and other Storage Engine) code of SQL Server 2005
May 11, 2009 at 5:25 pm
Here's issue. I am not able to backup that corrupted database. This is the error it gives...
BackupIoRequest::WaitForIoCompletion: read failure on backup device 'E:\Data\abc.mdf'. Operating system error 23(Data error (cyclic redundancy check).).
Please let me know your view on it.
May 11, 2009 at 7:19 pm
You should really start a new thread for each new issue.
Your database has IO-susbsystem caused corruption in it. Run DBCC CHECKDB (yourdb) WITH ALL_ERRORMSGS, NO_INFOMSGS to find out the extent of the corruption, and allow you to figure out how best to proceed.
I take it you have prior backups that you can restore from?
Paul Randal
CEO, SQLskills.com: Check out SQLskills online training!
Blog:www.SQLskills.com/blogs/paul Twitter: @PaulRandal
SQL MVP, Microsoft RD, Contributing Editor of TechNet Magazine
Author of DBCC CHECKDB/repair (and other Storage Engine) code of SQL Server 2005
May 12, 2009 at 1:36 am
RPSql (5/11/2009)
Here's issue. I am not able to backup that corrupted database. This is the error it gives...BackupIoRequest::WaitForIoCompletion: read failure on backup device 'E:\Data\abc.mdf'. Operating system error 23(Data error (cyclic redundancy check).).
Please let me know your view on it.
Please don't post the same question in multiple places. It just means that people are going to be repeating themselves
No more replies to this question here please. Direct replies to http://www.sqlservercentral.com/Forums/Topic714637-146-1.aspx
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
April 2, 2018 at 12:06 am
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