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sample_ms in sys.dm_io_virtual_file_stats and Data Types

Paul Randal points out an interesting bug:

A prior student emailed me yesterday about some strange behavior of the sample_ms column in sys.dm_io_virtual_file_stats. It’s supposed to be the number of milliseconds since the SQL Server instance has been started. He has a SQL Server 2016 instance that’s been running since August 2019, and it shows the following:

ms_ticks from sys.dm_os_sys_info: 51915112684 (which works out to be August 28, 2019)

sample_ms from sys.dm_io_virtual_file_stats: 375504432 (which works out to be about 4.5 days)

Read on to get a determination and an alternative in case you’re using that field.