Simulating Patch/Driver update without rebooting ESXi Host

I was reading Mostafa Khalil's Storage book and came across with a fantastic option available with esxcli command using which you can simulate the patch update or any other Async Driver Update and you can see if the update will succeed or fail if there is any dependencies  on other packages.

You can first go through an installation dry run to verify if there are any problems as it would tell if there is any dependency which needs to removed as well. 

e.g. I am putting here the bn2nx driver for a 10 GB Braodcom NIC and I have copied the the zip file under /vmfs/volumes/bcm directory

esxcli software vib install -d /vmfs/volumes/bcm/BNX2X.zip --dry-run

This is a verbose version of the above command where we are defining the -d option

esxcli software vib install --depot /vmfs/volumes/bcm/BNX2X.zip --dry-run

Now once the command finished running you will see the output contains an entry with "Reboot Required: false", which means that at this time reboot of the ESXi host after the installation is NOT required. As this was just a simulation only but when you actually decide to put the patch/driver update you may need to reboot the host for certain services to be restarted or certain driver modules to be loaded upon the restart. 

You can run /sbin/services.sh restart or if you are in / directory then just run services.sh restart, which will restarts all the services on that host. 

This can only run from the ESXi Shell via SSH or locally on the ESXi host using DCUI/ILO/DRAC/RSA/KVM etc etc.

With the above command it will make possible for you to determine and plan the maintenance window accordingly and not affecting the production environment at all.

This command can let you know if you need any other update/dependency (if there is/are any) beforehand so that you can put them on the host before applying the actual driver/patch update.

Generally this command is used as one of the advanced options during the Installation/Upgrade of the ESX host using the kickstart script (ks.cfg). You can find about it more in the online documentation for vSphere here.

Hope you will find this information useful.

Care and share.