I am about to try to upgrade my small (1 Virtual Center and 4 ESX hosts) vSphere 4.1 environment to 5.1. My virtual center database lives on a separate SQL Server 2008R2 server. My virtual center server is virtual, if that matters. I have upgraded my licenses, and am reading the documentation, to try to formulate a plan that is fairly immune from causing any downtime to my virtual machines.
I am trying to devise a series of steps that are all fairly small, and such that each step doesn't harm anything, so that if I encounter trouble, I can take my time about resolving it. Then, when that step is stable, I can continue to the next step. I want to tell you what I have in mind, ask a question here and there, and hope you can point out any mistakes I'm making, and answer my questions. The big picture is:
1. Upgrade Virtual Center, and give it a few days to show me any problems before doing anything else.
2. Upgrade ONE ESX 4.1 host to ESXi 5.1. Convince myself things are okay, before doing any more.
3. Upgrade the other three ESX 4.1 hosts. Make sure all is well.
4. Create new LUNs, formatted with the new VMFS, move my VMs to them, and remove the old LUNs.
If there's anything wrong with that basic plan, please let me know.
More details and questions:
Question: The docs say my Virtual Center server, running single-sign on, inventory service, and virtual center server, will need TEN GIGS of RAM. Is that true? That sounds insane to me.
Question: Can I install single signon on my Virtual Center 4.1 server HARMLESSLY? That is, will its installation prevent the 4.1 virtual center server from working? I hope I can, since that's a totally new feature that I may have trouble with. I don't want to get into a situation where my old virtual center server doesn't work, and I can't get the new one working.
Question: Can the VI client 4.1 talk to Virtual Center 5.1? Can the VI Client 5.1 talk to Virtual Center 4.1? I hope the answer to one of those is 'yes'.
Step 1: Create a backup of my virtual center VM (with Vranger, if it matters), and a backup of my SQL database.
Step 2: Install Single Signon. Here is where I hope this doesn't stop Virtual Center 4.1 from working.
Step 3: Upgrade Inventory Service and Virtual Center to 5.1
Step 4: Install VI Client 5.1 on the Virtual Center VM, and on my desktop from which I usually manage my environment.
Step 5: Wait until I'm comfortable that all is well. This may be a day or two (or more).
Question: How should I upgrade my hosts for maximum safety? I prefer to put a DVD in the drive, and do it from the console, unless that's not a good way.
Question: Before I upgrade a host, should I remove the fibre channel cables, so it cannot see my VMFS LUNs? I think I read that somewhere, and it sounds like a good thing to do, even if I didn't.
Step 6: Upgrade one ESX 4.1 host to ESXi 5.1. Move a couple of non-essential VMs to it, and give it a day or two to settle.
Step 7: Upgrade the other three ESX hosts.
Step 8: Wait till I'm really, really comfortable with things.
Step 9: Create new VMFS5 LUNs, migrate my VMs to them over time, and remove the old LUNs.
I would greatly appreciate any advice and warning that you might have.