possible i/o issues ?

  • Hi

    In the windows system error log we have started to receive the following error:

    "The system failed to flush data to the transaction log. Corruption may occur" (event id 57)

    I get several of these errors then:

    "The default transaction resource manager on volume \\?\Volume xxxxxxxxxxxxxxx\ encountered a non-retryable error and could not start. The data contains the error code".

    Then an informational level message of:

    Service stopped - Source:Virtual Disk service

    In the sql error log I see:

    I/O Is frozen on database xxxx. No user action is required. However, if I/O is not resumed promtly, you could cancel the backup.

    I/O was resumed on database xxxx. No user action is required.

    Database backed up. Database:xxxx creation date , pages dumped.......

    These errors have started to occur at the same time every evening on our servers which are hosted by a third party.

    I am wandering what the significance of this is and how come its always at the same time ? Full database backups are not scheduled for this time yet the log says they occurred !!

  • The first thing I would run is this:DBCC CHECKDB (<Database Name>) WITH NO_INFOMSGS, ALL_ERRORMSGSand post the entire output. Once corruption has been ruled out then we can start investigating from there.



    Microsoft Certified Master - SQL Server 2008
    Follow me on twitter: @keith_tate

    Forum Etiquette: How to post data/code on a forum to get the best help[/url]

  • Keith Tate (8/1/2014)


    The first thing I would run is this:

    DBCC CHECKDB (<Database Name>) WITH NO_INFOMSGS, ALL_ERRORMSGS

    and post the entire output. Once corruption has been ruled out then we can start investigating from there.

    Just fixing the code example.

    FWIW - when pasting code, a CRLF after the open code block will help prevent the conversion of < to lt and > to gt, amongst other things.

    Jason...AKA CirqueDeSQLeil
    _______________________________________________
    I have given a name to my pain...MCM SQL Server, MVP
    SQL RNNR
    Posting Performance Based Questions - Gail Shaw[/url]
    Learn Extended Events

  • Thanks Jason!



    Microsoft Certified Master - SQL Server 2008
    Follow me on twitter: @keith_tate

    Forum Etiquette: How to post data/code on a forum to get the best help[/url]

  • Ok I have ran checkdb and the results show no errors:

    DBCC CHECKDB (MyDatabase) WITH all_errormsgs, no_infomsgs executed by JoeBloggs found 0 errors and repaired 0 errors. Elapsed time: 0 hours 3 minutes 4 seconds. Internal database snapshot has split point LSN = 00050393:0006ffba:0001 and first LSN = 00050393:0006ffb9:0001.

    So what is causing the i/o freeze and the subsequent database backup that the error log refers to ?

    We do not have any scheduled backups at the time this happens !

    I have read something about Volume Shadow Copy services which causes i/o to freeze whilst it takes a snapshot - could this be the problem ?

  • I/O frozen & resumed could be Shadow Copy.

    Look for snapshots:

    USE msdb

    GO

    SELECT server_name, database_name, backup_start_date

    FROM backupset

    WHERE is_snapshot = 1;

    Maybe your hosting service is backing-up the entire VM?

    If you are taking diffs, you might want to try a test restore using a full before and diff after the mysterious backup run.

    Chris

  • looks like your third party hosts are running some sort of third party backup, have you spoken to them?

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