I/O when using encryption/compression Thanks for your reply.
No, it's not CPU - it's I/O operations as explained here
https://www.oreilly.com/library/view/windows-server-2008/30000LTI00084/30000LTI00084_ch15sec22.html
This is the CPU in the last 28 days, obviously not loaded at all:
The machine in itself is not overloading because of these I/O operations. Just interested to know of anything that could cause this behaviour. You can see a spike in Disk Transfer/sec and read/write per second - the numbers are too small to impact the overall machine but higher than previous volumes.
Also note this machine has five drives but this change in I/O profile only happened on the boot drive - the other drives (SQL database, logs, paging file) aren't affected. It's a VM, 16 cores using 10 threads per backup plan.
In any case, I have asked support about this and will update later if anything comes to light.