I/O is Frozen on Database. You are scanning your SQL Server Logs and discover the following error messages. There may be a long list of them, one frozen and one resumed for each database on your SQL Server.

I/O Is Frozen On Database

spid61,Unknown,I/O is frozen on database [master]. No user action is required.
spid61,Unknown,I/O is frozen on database [model]. No user action is required.
spid61,Unknown,I/O is frozen on database [msdb]. No user action is required.
spid61,Unknown,I/O is frozen on database [databaseName1]. No user action is required.
spid61,Unknown,I/O is frozen on database [databaseName2]. No user action is required.
spid61,Unknown,I/O was resumed on database [master]. No user action is required.
spid61,Unknown,I/O was resumed on database [model]. No user action is required.
spid61,Unknown,I/O was resumed on database [msdb]. No user action is required.
spid61,Unknown,I/O was resumed on database [databaseName1]. No user action is required.
spid61,Unknown,I/O was resumed on database [databaseName2]. No user action is required.

The error message doesn’t sounds good, I/O frozen… Your SQL Server needs its I/O, and how could frozen I/O be anything but bad?

Well it turns out that when Veeam, Veritas, Symantec Business Continuance Volume (BCV) or other third party backup tools that uses a VSS (Volume Shadow Copy Services), it temporarily freezes the I/O, then quickly resumes it. Keep in mind that Veeam for instance is a really awesome tool, that just happens to use a built in SQL Server feature to use snapshots on the backup. Veeam an other backup tools do this to get the most solid backup possible when a virtual machine is being backed up.

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