On SQL Server 2005 log report, everyday I receive the following message:

I/O is frozen on database databasename.

Is it serious ? How to resolve it ?

  • 3
    What do you use for backups? Something like VSS? Jul 24, 2012 at 12:28
  • The only time I've seen this in my own environment is when VSS-based backups have been running so that would be my guess too.
    – georgeb
    Jul 24, 2012 at 14:33
  • 2
    This is how certain file level backup systems (like VSS) ensure consistency of the backup, they explicitly freeze IO on the database, see A Guide for SQL Server Backup Application Vendors. You need to identify which such backup system is causing it, who installed it and why etc etc. Jul 24, 2012 at 14:35
  • YES, you guys were right. It was VSS, which caused this messgae in SQL Server Log Jul 25, 2012 at 12:32

1 Answer 1


VSS is being used to backup your database.

Edit: [Thanks Colin]

This causes the logged 'I/O is frozen' message. It is not serious. No need to resolve it.

Be warned, your database restore chain may be impacted, in which case it is serious. If you backup strategy is weekly full, daily diff, hourly tran per day - 8am -5pm; a daily snapshot VSS backup will cause your diff's to fail.


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