“sys.Dm_io_virtual_file_stats” is one of the excellent DMV in SQL Server. Generally people used talk about processor, memory and network a lot but always overlook disk capacity. You can’t read/write more than the capacity of your disk, no matter how many processor/core you have, how much RAM you assign to SQL Server or how fast your network is.
Whenever I have a situation to deal with performance issue of SQL Server, I never forget to use “sys.Dm_io_virtual_file_stats” DMV. I have very small script but it can save so many hours which you suppose to spend in finding a bottleneck of performance in SQL Server whenever disk is a culprit.
Each disk has capacity to read and write, if your workload is generating more read/write then the capacity of your disk, you can’t achieve optimal performance of other hardware you have.
Here is the script to measure disk IO capacity, have a look at it:
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