because I can…
Traditionally, historically, we use to keep our vCenter physical. Nowadays it’s fairly well accepted, and there’s even VMware best practices, to virtualize vCenter, which is the direction I see most taking. I almost feel dirty telling people I still choose not to virtualize vCenter. I can feel my street cred dropping. I feel that I’m losing a battle here and my times of running vCenter on separate physical hardware are coming to an end.
I choose to run my current vCenter on physical servers. It has local RAID disks separate from a SAN. A local SQL Server not reliant on a shared SQL server. It also runs a local DNS accepting zone transfers from an internal DNS. Physical servers generally tend to be way gruntier than a vCenter will usually need too.
This gives the vCenter real high independence from the rest of the infrastructure. During infrastructure maintenance I can power down an entire ESXi datacenter farms and still have vCenter connectivity. I can performance SAN maintenance with complete independence from vCenter storage and without fear that a datastore that could have been hosting a vCenter VM might be effected.
I’ve had a lot of great success using this method for vCenter. Infrastructure maintenance windows seems to go much more smoothly when I have full vCenter connectivity. The physical server actually turns out to be a good jump box during these periods as well. I’ve even had unplanned outages that have been recovered from much quicker had I not had an independent vCenter.
In normal operation running vCenter virtualized isn’t an issue. It just works, right! There’s little tricks you do, of course, to make life easier for yourself though. You usually disable DRS on the vCenter VM to make it easier to identify which ESXi host it’s running on. You put a High restart priority on the VM itself to cater for HA situations.
In my eyes though, that’s just thinking small events. We’re not foreseeing how we’ll manage the VMware infrastructure during large scale failures. We’re running vCenter on the same SAN storage as our production VMs. A SAN failure of some sort can instantly affect our vCenter and ability to manage our Vmware environment. I’m sure many of us install the vCenter DB onto a shared SQL server too. What happens when that SQL server goes through maintenance, has an outage, or is just under high load? vCenter becomes effected immediately.
Perhaps I’m placing way too much importance on vCenter? Maybe I’m just stubborn and old school? I really don’t know. The latest version of the vSphere 5.1 virtual appliance is really good. So good that I’m considering moving away from the Windows version permanently. I have a feeling this is going to start leading me down the virtualized vCenter path forever.