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In Resource Monitor, under Disk > Disk Activity, a list of files is shown along with the disk read/write B/sec being performed on each. When memory is paged to disk (ie. virtual memory is written), is it reported as write activity against the pagefile.sys? When a hard fault occurs (ie. virtual memory is read), is it reported as read activity against pagefile.sys?

Background

We had performance problems with a large database. Resource monitor showed copious disk activity, mostly reads, against the mdf file and sqlservr process; two orders of magnitude greater than usual load. It did not appear to be due to any operation performed by our applications. Memory was also constrained at the time. I'm wondering if Resource Monitor reported virtual memory paging as Disk I/O on the db file and sqlservr process rather than on pagefile. A reboot and upsize of the VM brought disk I/O back to normal levels.

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Yes, the Resource Monitor is just reporting I/O activity - independently of the cause or target file name. This includes pagefile.sys.

I'm wondering if Resource Monitor reported virtual memory paging as Disk I/O on the db file

No, there is no logic that is able to 'fake access file names' in ressource monitor.

It is more likely that your database process just does a lot more read's and writes to your database file when there is a memory constraint (and it is no longer able to cache the accessed data). Database access speed, especially whe doing a lot of read operations, scales almost linear with memory size.

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