trace flag 815

  • Hi Guys,

    Recently I have been recieving 832 errors on my sql server. One time it actually corrupted my database and I needed to do a restore.

    We have been talking to Microsoft who have looked at many things (sqlio, logs etc). One of the last things they suggested was getting the vendor to do a hardware check. Our hardware guys are sure that there is not a hardware problem

    Anyway I did some looking around and found that trace 815 and 818 could help diagnose. The doco I read was that I should not do without consulting microsoft - so I asked them about it and they seem to think it is a good idea.

    The thing I need to ask and could not claridy with microsoft is:

    If a dump is caused from a result of trace 815, does that prevent an external process from writing into sql server's memory?

  • From what I understand, no, but it will help you track the source of the problem.

    Ask your hardware people for the results of the memory diagnostics. "We're sure it's fine" != "It is fine"

    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
  • Hi

    I suggest you look at the errorlogs, check the error.

    Get the address and details of the database and the associated LUN on SAN.

    Check for path failovers, find out how the caching is being done.

    Don't say it's an error on the kit, people will just get their backs up.

    What storage vendor are you using? what is the aligntment

    You can get this with dbcc fileheader (dbname), sector size.

    the is an oldish doc with some good info on those. Just google for SQLIOBasic. It will be under SQL2000 in technet.

    Are you getting any errors in memory, on the OS side.

    Cheers

    Jannie

  • Jannie-186227 (7/19/2011)


    Get the address and details of the database and the associated LUN on SAN.

    Check for path failovers, find out how the caching is being done.

    Don't say it's an error on the kit, people will just get their backs up.

    What storage vendor are you using? what is the aligntment

    You can get this with dbcc fileheader (dbname), sector size.

    the is an oldish doc with some good info on those. Just google for SQLIOBasic. It will be under SQL2000 in technet.

    Error 832 is not an IO-related error. Error 832 means that a page was read into memory, it was checked at that time and it was fine (correct checksum, valid page). At a later point SQL went to make changes to it (still in memory) and the page had changed since being brought into memory.

    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

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