To continue my experiences and planning for the upgrade to vSphere, here is the next stage.

First and foremost you have to understand what the process is for upgrading your environment. So off I went to the vSphere Upgrade Guide. I highly advise you read this document from start to finish , but to lay it down in short the process is:

1. Upgrade vCenter Server (including all additions)
2. Upgrade the Hosts
3. Upgrade the Datastores (not relevant in my case)
4. Upgrade VM’s

You need to understand - what will be affected (and what will not!) in each and every stage of he process.

1. During the Upgrade - Services provided by the vCenter Server will not be available
• DRS
• VMotion
• Console Access to the VM (unless you go in per host
• HA will continue to work
2. During the host upgrade you will need enough resources on the other members of your cluster to allow for upgrade of each host - without downtime for your VM’s
3. Datastores - was not relevant in my case.
4. Virtual machine will need to be powered off and upgraded - which will mean downtime for all the VM’s

You can of course plan to take the whole infrastructure down at the same time (vCenter, ESX hosts, VM’s and all) but I think that is completely not necessary seeing that this can be done in stages with minimal disturbance to you Infrastructure.

Coming up next vCenter Server Upgrade.