Lot of times depending on the VMware components you are using its always better to check which component to upgrade 1st whenever there is a newer version available.
Now this is a big question for any Organization as its affects the whole chain of Maintenance, downtime, change management requirements etc. etc.
If the downtime is involved in cost and other losses then such upgrade process must be thought out carefully before proceeding further.
Depending on the products in use sometimes people have the ability/luxury of having a standby/Dev/Test/Lab environment where they can do such upgrade first and verify if its affecting anything in such environment and if everything successfully upgraded then you can roll out the same steps in your Production environment.
Now look at the following Table which will clear up most of your doubts
Now as you can see the VCD (vCloud Director) is the 1st one in the process of upgrade. As the upgrade starts with the lowest number First you go with the same recommendation for all the products and related upgrade path (whether you run only few, all or some of them) and you should not be having any issues.
I would also suggest to search
http://kb.vmware.com/ and the
Release Notes for each products involved, for any known issues/gotchas during the upgrade so that you can take care of them before you proceed with the Upgrade.
Now here if you are using Cisco Nexus 1000v then you need to make sure before you upgrade your ESXi/vCenter Server, please make sure that the VSM/VEM version are supported/Compatible otherwise after upgrading your vCenter server you may end up in a dead water with NO connectivity on the VMs/ESXi if hosts if everything is managed through Nexus 1000v. With your existing version of VSM you can check up the
Cisco's website for the Compatibility of ESXi/VC.
As Nexus 1000v is a Cisco product the above Matrix is not reflecting the same but it will be definitely grab a spot after vCenter/ESXi host upgrade paths.
There is a published
KB 2037630 available too for more information which you can refer if you are running SRM/VR and VDP solution in your environment and which will guide you on the steps of overall upgrade.
And suppose you are running vCenter Server Appliance then the above KB will not help but instead refer the
KB 2031331.
Enjoy upgrading VMware Environment !!
Share and care !
Cheers.
