VMware VirtualCenter running inside virtual machine - part one

I finished another installation of virtualized environment recently. I had to get rid of old machines and to deploy virtualization on couple of new SUN Blade 6250 modules (installed in SUN Blade 6000 Modular System) connected to SUN StorageTek 2510 iSCSI disk array. The final solution had to pass high-availability conditions.

The VMware ESX Server 3.5 hypervisor was installed on both of blades and deployed in high-availability mode. It requires VirtualCenter Server to be installed to configure VMware cluster. But does it have to be installed on a standalone machine?

VMware officially supports VirtualCenter Server running inside a virtual machine (further denoted as VC VM). Such configuration supports VMware HA as well. But it will pay to keep some basic rules in mind. Let's go over them:

1. VC VM should have allocated enough resources - set CPU/MEM reservations and shares sufficiently to avoid of running out of resources because this machine is vital for virtual infrastructure. It has to be prioritized over the other virtual machines.
2. Remember to monitor the machine. That means configure a simple alarm to check CPU/MEM usage. E.g. it can be trigerred if the resource usage is over 90%.
   
3. VC VM should be deployed with security rules in mind. Define which users can access it and limit their permissions (configure user roles with help of Active Directory).
   

The list above doesn't contain obvious rules like hardware requirements for server, installation of MSSQL database separately and similar. These rules are the same as for standalone VirtualCenter installation. Next, we are going to discuss the question what to NOT perform with VC VM:

1. Never cold-migrate VC VM! The machine has to be powered off first.
2. Don't try to clone VC VM if you are deploying version of Virtual Infrastructure before 3.5. The version 3.5 supports virtual machine cloning on the fly.
3. Try to avoid of any operation with VC VM AKA virtual machine hardware reconfiguration which may require to power it down. If you need to do it, connect directly to the related ESX host, power VC VM off and reconfigure it without loosing management connection.
   

It remains to discuss the stuff around VirtualCenter virtual machine installation and to realize if such configuration will bring something new compared to standalone installation. But about it by the next time.