Best Practices: running vCenter virtual (vSphere)

Yesterday we had a discussion on running vCenter virtual on one of the internal mailinglists. One of the gaps identified was the lack of a best practices document. Although there are multiple for VI3 and there are some KB articles these do need seem to be easy to find or complete. This is one of the reasons I wrote this article. Keep in mind that these are my recommendations and they do not necessarily align with VMware’s recommendations or requirements.

Sizing

Sizing is one of the most difficult parts in my opinion. As of vSphere the minimum requirements of vCenter have changed but it goes against my personal opinion on this subject. My recommendation would be to always start with 1 vCPU for environments with less than 10 hosts for instance. Here’s my suggestion:

• < 10 ESX Hosts
  • 1 x vCPU
  • 3GB of memory
  • Windows 64Bit OS(preferred) or Windows 32Bit OS
• > 10 ESX Hosts but < 50 ESX Hosts
  • 2 x vCPU
  • 4GB of memory
  • Windows 64Bit OS(preferred) or Windows 32Bit OS
• > 50 ESX hosts but < 200 ESX Hosts
  • 4 x vCPU
  • 4GB of memory
  • Windows 64Bit OS(preferred) or Windows 32Bit OS
• > 200 ESX Hosts
  • 4 x vCPU
  • 8GB of memory
  • Windows 64Bit OS(requirement)

My recommendation differ from VMware’s recommendation. The reason for this is that in small environments(<10 Hosts) there’s usually more flexibility for increasing resources in terms of scheduling down time. Although 2 vCPUs are a requirement I’ve seen multiple installations where a single vCPU was more than sufficient. Another argument for starting with a single vCPU would be “Practice What You Preach”. (How many times have you convinced an application owner to downscale after a P2V?!) I do however personally prefer to always use a 64Bit OS to enable upgrades to configs with more than 4GB of memory when needed.

vCenter Server in a HA/DRS Cluster

1. Disable DRS(Change Automation Level!) for your vCenter Server and make sure to document where the vCenter Server is located (My suggestion would be the first ESX host on the cluster).
2. Make sure HA is enabled for your vCenter Server, and set the startup priority to high. (Default is medium for every VM.)
3. Make sure the vCenter Server VM gets enough resources by setting the shares for both Memory and CPU to “high”.
4. Make sure other services and servers on which vCenter depends are also starting automatically, with a high priority and in the correct order like:
   1. Active Directory.
   2. DNS.
   3. SQL.
5. Write a procedure to boot the vCenter / AD / DNS / SQL manually in case of a complete power outage occurs.

Most of these recommendations are pretty obvious but you would be surprised how many environments I’ve seen where for instance MS SQL had a medium startup priority and vCenter a high priority. Or where after a complete power outage no one knows how to boot the vCenter Server. Documenting standard procedures is key here; especially know that with vSphere vCenter is more important than ever before.

Source:
http://kb.vmware.com/kb/1009080
http://kb.vmware.com/kb/1009039
ESX and vCenter Server Installation Guide
Upgrade Guide