Like the title said, I need to upgrade from vSphere 4.1 to 6.5,
and I was looking for information on the best way to go about
it, as well as any tips or best practices for the upgrade process.
Looks like you will have to upgrade to ~5.5 U2 and then to 6.5
The Interoperability Matrices are your friend here and will show you what can be upgraded to what for all the main VMware products:
There may be other variables that need to be accounted for such as the DB-type of your vCenter and whether this can be upgraded:
Another thing to consider that will likely require upgrading is the VMFS datastore versions
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Another option is to build new. I went with this route when I went from 4.1 to 5.5.
We built new new vSphere host at 5.5 using an extra host we pulled out of the cluster. We then deployed a new vCenter server. We then removed another host, rebuilt it using the 5.5 ISO and joined it to the new vCenter in the cluster with the 1st host. We then removed 1 host at a time from the 4.1 vCenter and joined them (live) into the 5.5 vCenter, in the same cluster as the 1st 2 (making sure to have DRS & HA off). We were then able to migrate the VMs to the 5.5 hosts with 0 downtime. As we moved VMs, we rebuilt the 4.1 hosts using 5.5, until all hosts were at 5.5.
I usually prefer this method as you're getting a clean install each time.
However, like TheBobkin said, you'd need to go to 5.x first before going to 6.5.
To take advantage of all the changes I would definitely recommend that you build a new environment rather than upgrade the old one.
Fresh installation would be good practice instead of upgrade.
6.5 also gives you the ability to build an appliance and thus reduce the need for a Windows license.
matthew1992 I can only agree with BenLiebowitz and battybishop , build a new 5.5 environment and migrate to it, will give you much cleaner migrations and servers, if your upgrades fail you will be in a world of pain that you can avoid.
In this case, I prefer a fresh install.
Many changes in vsphere between 4.1 and 6.5.
Probably you need to install a new Windows 2012
i have never upgraded any version of vcenter. I choose to build a new and separate vcenter, then migrate the entire environment out of the old and into the new.
If you aren't using dvswitches, you are half way there!!