VMware Update Manager comes with the very good utility called as Pre-Check Remediation report which helps you to prevent the issues which can occur at the time of Remediation of vSphere Object. So In this post we will see on What is Pre Check Remediation in Update Manager & How to Perform Pre Check Remediation on ESXi Hosts.
Basically Pre-Check Remediation is a check that is performed on the host or the cluster that displays a table that lists possible problems that might prevent a successful remediation, and provides recommendation on how to fix the issues. You can easily generate Pre-Check Remediation report in VMware Update Manager.
Below are the Pre-Check Reports that can be generated and recommended action is given based on the criteria. This both the Table information is taken from VMware Documentation.
Pre-Check Remediation Report for Clusters:
| Sr No | Current Status | Recommended Action | Description |
| 1 | Is DPM disabled? | Disable DPM on the cluster. | If a host has no running virtual machines, DPM might put the host in standby mode before or during remediation and Update Manager cannot remediate them. Disable DPM on a cluster to ensure that the remediation process is successful. |
| 2 | Is DRS enabled?
| Enable DRS on the cluster.
| DRS enables vCenter Server to place and migrate virtual machines automatically on hosts to attain the best use of cluster resources. |
| 3 | Is HA admission control disabled?
| Disable HA admission control.
| HA admission control prevents migration of the virtual machines with vMotion and the hosts cannot enter maintenance mode. Disable HA admission control on a cluster to make sure that remediation is successful. |
| 4 | Is EVC disabled on the cluster?
| Enable EVC on the cluster.
| EVC ensures that all hosts in a cluster present a common set of CPU features to virtual machines. EVC must be enabled so that the virtual machines are migrated successfully within the cluster during remediation. |
| 5 | Is vSAN health check successful?
| Check vSAN Health Check Page for Issues | The vSAN health check performs a series of tests on the hosts in the vSAN cluster. The vSAN health check must succeed to ensure successful remediation of hosts in the vSAN cluster. |
Pre-Check Remediation Report for Virtual Machines:
| Sr No | Current Status | Recommended Action | Description |
| 1 | CD/DVD drive is attached. | Disconnect the CD/DVD drive.
| Any CD/DVD drives or removable devices connected to the virtual machines on a host might prevent the host from entering maintenance mode. Remove or Disconnect it for successful Remediation. |
| 2 | floppy drive is attached. | Disconnect the floppy drive.
| Any floppy drives or removable devices connected to the virtual machines on a host might prevent the host from entering maintenance mode. Remove or Disconnect it for successful Remediation. |
| 3 | FT is enabled for a VM | Disable FT on the virtual machine.
| If FT is enabled on for any of the virtual machines on a host, Update Manager cannot remediate that host. |
| 4 | VMware vCenter Server is installed on the VM and DRS is disabled on the cluster. | Enable DRS on the cluster and ensure that VMs can be migrated with vMotion. | One of the VM in the cluster runs the vCenter Server instance that you currently use. If you enable DRS on the cluster, vCenter VM will be migrated to Another Host for successful Remediation. |
| 5 | VMware vSphere Update Manager is installed on the VM and DRS is disabled on the cluster. | cluster and ensure that VMs can be migrated with vMotion. | One of the virtual machines in the cluster runs the Update Manager instance that you currently use. If you enable DRS on the cluster, Update Manager VM will be migrated to Another Host for successful Remediation. |
So now we know what are Pre-Check Remediation , Let’s see How to Perform Pre-Check Remediation:
Step 1:
Select the Cluster on Which you want to generate Pre-Check Remediation Report.
Go to Updates Tab.
Select Host Updates.
Here you can see Pre-Check Remediation.
Click on Pre-Check Remediation to generate Report.
Step 2:
Now you will see Pre-Check Remediation Report is generated and all the issues which can prevent Remediation is displayed:
So now based on the Pre-Check Remediation Report you can perform the recommended action and Re-Run Pre-Check to ensure that your remediation goes successful without any issues.
It is the best practice to use this Pre-Check Remediation so you can avoid any issues which can prevent in the Remediation Process.
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Source: VMware Documentation.
