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DBCC checkdb doest show errors but BACKUP shows error 23(Data error (cyclic redundancy check)

  • May 1, 2011 at 2:55 pm

    #238929

    Hi!

    I have a DB that is working apparently fine, but when I try to backup it shows the error 23(Data error (cyclic redundancy check). I perform then the recommended DBCC checkdb and the result was clean with no errors. I can connect to this DB correctly and all the data seems to be OK. I try many tools to obtain a backup from this DB with no success. I also try to copy the .mdf file and no sucess either.

    Please HELP!! I have a very old backup from this DB and I ness to save this one!!

    Thanks in advance for any idea.

    Dena

  • May 1, 2011 at 3:22 pm

    #1318254

    Post the exact errors please.

    What was the CheckDB command you ran?

    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

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

  • May 9, 2011 at 8:53 pm

    #1322065

    One other thing you can do is check windows event log and see if there are any disk errors reported.

  • December 9, 2015 at 3:06 am

    #1844837

    I have the same problem.

    The error is:

    Backup failed for server -> Additional Information

    System.Data.SqlClient.SqlError: A nonrecoverable I/O error accourred on file Company.ldf:" 23(Data error(cyclic redundancy check).).

    (Microsoft.SqlServer.Express.Smo)

    Can anyone help me?

  • December 9, 2015 at 3:19 am

    #1844839

    CheckDB doesn't check the log, so it wouldn't pick this up.

    When you have some downtime:

    Switch DB to simple recovery model.

    Checkpoint

    Shrink log to 0

    Regrow log to full size in sensibly sized chunks (may as well fix VLFs at the same time), see Kimberly Tripp's blog post on transaction log throughput

    Switch back to full recovery (assuming it was in full recovery before)

    Take a full backup (and test the backup by restoring it elsewhere)

    Do some investigation into the IO subsystem to figure out why the IO system is giving CRC errors.

    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

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

  • December 10, 2015 at 1:52 am

    #1845113

    Thank you GilaMonster, I will try it.

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