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vCenter Server vDesign: Physical vs Virtual Machine
Over the last years there have been some controversy over this topic: should vCenter Server be a physical or a virtual machine? There is a best solution or a best practice?
The most important aspect is that both solutions are supported by VMware. And the virtual solution is fully supported from VI 3.x, for more info see also the official paper: Running VirtualCenter in a Virtual Machine.
Note that in both cases minimum required must be guaranteed. The requirement for 2 CPU become a requirement of 2 vCPU (but note that, for small environment, it can run also on a single vCPU, although completly not supported).
vCenter Server dependency
In order to understand how is is possible to have a vCenter Server inside the virtual environment, it’s also very important understand with VMware service require a working vCenter Server:
- VMware HA require vCenter only for the initial setup, then HA works on the hosts.
- VMware vMotion and Storage vMotion require vCenter only to start the operation, then the operation will finish also without vCenter.
- VMware DRS/DPM can work only with vCenter.
- Template provisioning, cloning and customizing require vCenter.
- DVS can be modify only if vCenter Server is running (but data are “cached” also on the hosts).
- Of course VUM, Hosts Profiles, Statistics, … will not work without vCenter Server.
- From vSphere 4.x the licenses are still managed in a central way but without a license server.
In addition, you will also need to know where your DB server is located, cause if you loose DB connection, the vCenter Server service will stop! This is one of the service on which vCenter Server depends on it. For this reason in medium/small environment could be a good idea put the on the same server also the DBMS.
Physical solution: pro and cons
- With VI 3.x the license server can work also if ESX are down… this could be useful to power on the ESX and the VM
From vSphere 4.x licenses are assigned on each object… so no issue about it.
- It is not susceptible to a potential virtual infrastructure outage.
- Most scalable, cause performance are limited only by the power of server hardware.
But in vSphere 4.x the VM also can scale more…
- A dedicated physical server is required (on VI 3.0 was not recommended mix it with VCB or other services).
- Backup of vCenter Server must be done using tradition tools.
- Difficult to manage a disaster recovery solution (there is a specific solution from VMware: vCenter Server Heartbeat).
- Not easy solutions for Business Continuity.
Virtual solution: pro and cons
- You do not need a dedicated physical server (a way to reach a greater consolidation).
- vCenter Server is just an “appliance” (for small/medium environment also the database part can be put together).
- Faster to restore, you can use VMware HA to restart vCenter Server.
- Each backup solution that work for a VM work also in this case.
- Simple solutions for Business Continuity.
- If you have vMotion license you can move the VM to one host to another.
- If you have Storage vMotion license you can move the VM to one datastore to another.
- In VI 3.x, if license server is on vCenter Server, you can have some big problems after 14 days of downtime (see http://www.riccardoriva.com/archives/703).
- If you do not have vMotion license than you have to power-off vCenter Server to move between hosts (see vMotion section of How work without vCenter Server ).
- Without Storage vMotion license is not simple move vCenter between datastores.
- It is susceptible to a potential virtual infrastructure outage.
- It must contend for resources along with other VMs.
- In vSphere 5 it can increase the amount of vRAM assigned (remember the vRAM entitlement limit for each edition).
Best Practices for running a virtual vCenter Server
- http://searchvirtualdatacentre.techtarget.co.uk/news/column/0,294698,sid203_gci1512874,00.html? – VMware best practices: Why virtualise vCenter?
- For large environment, as suggested in the VMware vSphere: Design Workshop 4.x, a management cluster (with only 3 nodes) could be considered for vCenter Server and other management VM or VA (for example vMA). In this case most of the cons will not applied, because management and production clusters are using different hosts.
vCenter Performance as a VM
- http://www.blueshiftblog.com/?p=1206 – Should You Virtualize vCenter Server (and everything else?)
- http://www.vmware.com/resources/techresources/10162 – Performance of Virtualized SQL Server–Based VMware vCenter Database
P2V or V2P of vCenter Server
- The P2V conversion is very simple and can be managed by VMware Converter without problem.
- The V2P conversion could be a little complicated. See: Moving Virtual Center from VM back to Physical
- To move the SQL Server database see this KB: http://kb.vmware.com/kb/7960893 – VMware Self-Service- Moving the VirtualCenter SQL Database
- vCenter server physical or virtual
- vCenter on a VM v/s vCenter directly on hardware?
- Virtual Center as a Virtual Machine.
- Increase the availability of vCenter Server