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derrickonlineFlag for United States of America asked on

ESX/ESXi 3.5 to 4.1

I have two hosts running ESX or ESXi 3.5.  I want the hosts upgraded to 4.1.  My understanding is it's best to do a CLEAN install and not an upgrade.

So far I've already setup my vSphere server, populated licenses, etc.  In fact I've been running vSphere client managing my hosts and vms for a while now.  I just haven't upgraded my hosts or vms to 4.1 yet.

Quick Notes:
My vSphere server is a separate physical machine.

I keep reading that I should migrate my vms to another host, then clean install 4.1 on host, then migrate the vms back to the host.

Because I'm doing this off hours, I can shut down all the virtual machines.  Not an issue.  

Will the following work:

1.  HOST A.   -  Power down all VMs.  (FYI, all VMs run off a NAS device not local)
2.  HOST A.  - Clean install 4.1
3. HOST A.  - Launch vSphere, hosts & vms should import automatically?

I guess I want to ensure nothing happens to my VMs on the NAS.  Once I've upgrade my HOST A to 4.1 (doing a clean install) I should be able to launch vSphere and everything should reimport?  Or do I have to manually import my vms and/or host A?

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8/22/2022 - Mon

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After a clean install on the Host a you should be able to define your NAS access  and your  hosts should be there. All you would do is to add the machines but instead of create new you'll select the vmdk from the NAS and then you'll be back online soon.

If possible change your controller to SAS ( warning: this might cause problems with your windos systems so do this only for your Linux systems) This would improve your performance and good for further compatibility.

In short your way of upgrade will work.


Another option is to upgrade your vCenter first. Then you'll setup your new system and setup NAS connection. You can use vMotion connection to move a server between hosts. If you are not licensed to use vMotion try not to enter your license and you'll be in 60 day trial mode ...


Thanks for the additional input K.  Funny thing...I think I answered one of your open questions today before I asked mine.  
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All, the upgrade was a success.  Thank you for all your input.  I was nervous, but it went smoothly.

Awesome...thx for the f/u.