Virutalizing vCenter Server: Yes or No?

“Should I virtualize vCenter Server or not?!”.. This question is asked a lot, specially during preparing for new vSphere deployments. IMO, and in 99.9% of all cases I meet, I answer with “Yes!! Why not?”.

vCenter Server is a central part of your Management Layer of your infrastructure that requires high level of availability and performance. vSphere 5.x is capable of providing the required level of performance for vCenter Server itself or for any one of its components (SSO, Inventory Service or Web Client) as well as its required back-end Database. In the same time, virtualizing vCenter Server provides higher level of availability, using vSphere HA and the new SMP Fault Tolerance in vSphere 6.0.

Despite many advantages of virtualizing vCenter Server, there might be some corner cases in which the customer requirements force you to implement physical vCenter server, for example that I met personally: one customer had a policy not to change HW before 5 years of usage and he had some physical servers not used after virtualizing his environment on vSphere 5.1 (latest back then). Those servers would be idle for the next 3 years, and he insisted on creating a Physical Windows vCenter, with each component on a server!!

vCenter Server can be virtualized in two approaches: either on the same hosts of the production environment, which is called “Inband Approach” or on dedicated management cluster, which is called “Out-of-band Approach”. Following, is a comparison between the three approaches: Inband Virtualizing Approach, Out-of-band Virtualizing Approach and Physical Implementation Approach.

In-Band Virtualizing

Out-of-Band Virutalizing

Physical Implementation

In this strategy, management components are virtualized and hosted on the same Production Hosts/Clusters.

In this strategy, management components are virtualized and hosted on a separate infrastructure away from Production Hosts/Clusters.

In this strategy, management components are hosted physically on separate infrastructure away from production.

Advantages:
1-) The most easy approach.

2-) No additional financial costs.

3-) Easier to Manage.

4-) All vSphere features are used, like: FT, HA & DRS.

5-) HW Maintenance won’t cause disruption to vCenter Server in case of using DRS.

Advantages:
1-) Separation of Management Layer so that when an outage happens in production infrastructure, Management Layer components are protected.2-) Separate physical HW means, physical segregation and additional security.3-) Resources contention with Production Environment won’t occur.

4-) All vSphere features are used, like: FT, HA & DRS.

5-) HW Maintenance won’t cause disruption to vCenter Server in case of using DRS.

Advantages:
1-) Easier to manage the Management Layer, as there’s no new technical knowledge required.2-) Separate physical HW means physical segregation and additional security.
Disadvantages:
1-) Any outage happens in production infrastructure can affect Management Layer which can escalate the disaster. So, Availability and Redundancy is the main concern here.2-) Resources contention with Production Environment may occur.3-) Requires vSphere and Virtualization knowledge.

4-) Least secure approach.

Disadvantages:
1-) Additional financial cost for the additional hardware and licenses.2-) More management overhead to manage two separate clusters.3-) Requires vSphere and Virtualization knowledge.

Disadvantages:
1-) This approach can’t benefit from Virtualization advantages, like: HA, DRS or vMotion.

2-) Additional financial cost for the additional hardware and OS licenses.

3-) Different backup solution might be needed.

4-) 3rd Availability solution is needed to protect against failures.

5-) Bound to HW and hence, upgrades and so on will limit availability and life cycle.

Final Word:
From the previous comparison, it’s clear that virtualizing vCenter Server is considered mandatory wither using Inband Approach or Out-of-band Approach. In the end, it’s customer’s requirements that will drive you toward one of the previous approaches, even implementing vCenter Server physically. Whatever the approach of you’d take, you should also consider which vCenter Server you’d deploy (Windows/VCSA) and how you’d deploy vCenter Server components (SSO, Inventory Service, vCenter Server, Web Client and DB). You check my thoughts about these here and here, respectively.

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