"Unable to apply DRS resource settings on host" when running latency-sensitive VMs

Products

• VMware vCenter Server

Issue/Introduction

Symptoms:

• The summary page of an ESXi host in vSphere Client shows the a warning banner with the following message:

Unable to apply DRS resource settings on host.. This can significantly reduce the effectiveness of DRS.

• when looking in the system journal, the same error can be found:

  Nov 26 02:02:52 <vcenter> vpxd[6768]: Event [162290084] [1-1] [2023-11-26T01:02:52.369015Z] [vim.event.DrsResourceConfigureFailedEvent] [error] [] [<cluster>] [162290084] [Unable to apply DRS resource settings on host <host_name> in <cluster>. A specified parameter was not correct: spec.memoryAllocation. This can significantly reduce the effectiveness of DRS.]

• the log of the vCenter server service, /var/log/vmware/vpxd/vpxd-xxxxx.log, has the following entry:

  2023-11-26T02:02:52.368+01:00 warning vpxd[11112] [Originator@6876 sub=MoResGroup opID=HB-host-xxxxx@4086-44584e9d] Receive ConfigIssue when processing RP updates from host [vim.HostSystem:host-xxxxx,<host_name>] type vmodl.fault.InvalidArgument on ManagedObject vim.ResourcePool:resgroup-3018 for method vim.ResourcePool.updateChildResourceConfiguration

• when looking in /var/run/log/hostd.log on the host itself this is found:

  hostd.log:
  ..
  2023-11-26T01:02:42.337Z warning hostd[2100325] [Originator@6876 sub=Vmsvc.vm:/vmfs/volumes/datastore/folder/vm_name.vmx opID=HB-SpecSync-host-10257@2972391-11ec7f82-64-c13f user=vpxuser] Insufficient memory reservation for latency-sensitive VM. Expected memory reservation: 65536 MB, actual: 0 MB
  2023-11-26T01:02:42.339Z warning hostd[2100325] [Originator@6876 sub=Hostsvc.ResourcePool ha-root-pool opID=HB-SpecSync-host-xxxxx@2972391-11ec7f82-64-c13f user=vpxuser] UpdateChildResourceConfiguration: N5Vmomi5Fault15InvalidArgument9ExceptionE(Fault cause: vmodl.fault.InvalidArgument
  ..

Environment

VMware vCenter Server 7.0.x

Cause

This issue occurs due to one or more powered on virtual machines on the host, which are configured for high-latency sensitivity without having a complete memory reservation set as well.

Resolution

To remove the warning message and to prevent it's reappearance, verify if the VM needs to be configured for high latency sensitivity, depending on which please apply one of the following changes:
 

Option A - reconfigure the VM for normal latency sensitivity

• in vSphere Client right-click on the virtual machine and select "Edit Settings"
• in the "Edit Settings" Interface, change into the tab "VM Options" and expand the "Advanced" section
• almost at the bottom of this section the setting "Latency Sensitivity" can be found, change it to "Normal" and save the change with [OK]:

 

Option B - configure a full memory reservation:

• in vSphere Client right-click on the virtual machine and select "Edit Settings"
• In the "Edit Settings" dialog, in the tab "VIrtual Hardware", expand the "Memory" section
• Activate the check mark for "Reserve all guest memory (All locked) as in the image below
• Save the change with [OK]
• To activate the change, either migrate the virtual machine to another ESXi host, or power it off (shut down the guest OS and the VM itself) and back on again.

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