Recently some VMs went down during regular patching. When I checked they were not powered on and when I tried to power them on I got an error – “Invalid CPU reservation for the latency-sensitive VM, (sched.cpu.min) should be at least 6990 MHz.”.
What had happened is that someone had changed this VM latency sensitivity to “High” without doing proper CPU and RAM reservations. It would not have been a problem during a restart of a VM but I had set advanced setting called “vmx.reboot.PowerCycle” to TRUE since I needed VM to get some new CPU features. This setting causes VM to power cycle during normal OS reboot. And since the reservations were not properly done VM failed to power on. After fixing the reservations VM successfully powered on. The error message about RAM reservation looks like this – “Invalid memory setting: memory reservation (sched.mem.min) should be equal to memsize(4096)”.
To check the VM latency sensitivity using PowerCLI I use Virten.net.VimAutomation module written by Florian Grehl (his blog) – https://www.powershellgallery.com/packages/Virten.net.VimAutomation/1.3.0. This module has 3 useful commands for viewing and changing VM latency sensitivity – Get-VMLatencySensitivity, Get-VMLatencySensitivityBulk and Set-VMLatencySensitivity.