Monday, March 16, 2015

vSphere Datacenter Design – vCenter Architecture Changes in vSphere 6.0 – Part 1

Reposting my latest Blog entry from the VMware Consulting Blog:

http://blogs.vmware.com/consulting/2015/03/vsphere-datacenter-design-vcenter-architecture-changes-vsphere-6-0-part-1.html 

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As a member of VMware Global Technology and Professional Services at VMware I get the privilege of being able to work with products prior to release. This not only gets me familiar with the changes but allows for me to be able to question and figure out how the architecture will change in a datacenter.

I have recently been working on doing exactly this with vCenter 6.0 because of all the changes which are coming as a part of the release. One of my favorite things about vSphere 6.0, is actually the simplification of vCenter and associated services. Previously each individual major service (vCenter, Single Sign-On, Inventory Service, the vSphere Web Client, Auto Deploy, etc.) was installed as its own entity.  This added complexity and uncertainty to what the best way to architect the environment. 

As of vSphere 6.0, vCenter Server installation and configuration has been dramatically simplified. The installation of vCenter now consists of only two components which provide all services for the virtual datacenter. The two components are as follows: 

·         Platform Services Controller – provides infrastructure services for the datacenter.  The Platform Services Controller contains the following services:
o    vCenter Single Sign-On
o    License Service
o    Lookup Service
o    VMware Directory Service
o    VMware Certificate Authority

·         vCenter Services – The vCenter Server group of services provides the remainder of the vCenter Server functionality.  It includes the following services:
o    vCenter Server
o    vSphere Web Client
o    vCenter Inventory Service
o    vSphere Auto Deploy
o    vSphere ESXi Dump Collector
o    vSphere Syslog Collector (Windows) / VMware Syslog Service (Appliance)

When deploying vSphere 6.0 you therefore have to understand the implications of this change to properly architect the environment, whether that be a fresh installation or an upgrade. This is actually a dramatic change from previous releases, and one that is going to be sure a source of many discussions. 

To help prevent confusion, along with my colleagues from VMware Global Support and VMware Engineering, we have developed guidance on supported architectures and deployment modes. This two part blog series will discuss how to properly architect and deploy vCenter 6.0.

vCenter Deployment Modes

There are two basic architectures which can be used when deploying vSphere 6.0.  The deployment modes are as follows:

  • vCenter Server with an Embedded Platform Services Controller – This mode installs all services on the same virtual machine or physical server as vCenter Server.  This is ideal for small environments, or if simplicity and reduced resource utilization are key factors for the environment. The configuration looks as follows:  


  • vCenter Server with an External Platform Services Controller – This mode installs the platform services on a separate system to vCenter services.  The platform services must be installed first as it is a prerequisite for vCenter to be installed. This is ideal for larger environments, where there is a need for single pane of glass in the environment and there are multiple vCenter Servers in the same site. The configuration looks as follows:

Choosing an architecture to be used is critical as once the model is chosen, it is difficult to change and configuration limits could limit the scalability of the environment.

Enhanced Linked Mode

As a result of these architectural changes Platform Services Controllers can be linked together.  This enables a single pane of glass view of any vCenter server which has been configured to use the Platform Services Controller domain. This feature is called Enhanced Linked Mode and is a replacement for Linked Mode, which was a construct which could only be used with vCenter for Windows. The recommended configuration when using enhanced linked mode is to use an external platform services controller. 

Note:  Although using embedded Platform Services Controllers and enabling Enhanced Linked Mode can technically be done, it is not a recommended configuration.  See List of Recommended topologies for vSphere 6.0 (2108548) for further details.

The following are the recommended and not recommended options for Enhanced Linked Mode configurations:

  •  Enhanced Linked Mode with an External Platform Services Controller with No HA (Recommended)

In this case the Platform Services Controller is configured on a separate virtual machine and then the vCenter Servers are then joined to that domain, providing the Enhanced Linked mode functionality. The configuration looks like the following:

There are benefits and drawbacks to this approach.  The benefits include:

·         Less resources consumed by the combined services.
·         More vCenter instances are allowed.
·         Single-Pane of glass management of the environment

The drawbacks include the following:

·         Network connectivity loss between vCenter and the Platform Service Controller can cause outages of the services
·         More Windows licenses required (if on a Windows Server)
·         More Virtual Machines to Manage
·         Outage on the Platform Services Controller will cause an outage for all vCenter Servers connected.  High availability not included in this design

·         Enhanced Linked Mode with an External Platform Services Controller with HA (Recommended)

In this case the Platform Services Controllers are configured on separate virtual machines and configured behind a load balancer to provide high availability to the configuration.  The vCenter Servers are then joined to that domain using the shared Load Balancer IP address which provides the Enhanced Linked mode functionality, but is resilient to failures. The configuration looks like the following:

There are benefits and drawbacks to this approach.  The benefits include:

·         Less resources consumed by the combined services.
·         More vCenter instances are allowed.
·         Platform Services Controller configuration Highly Available

The drawbacks include the following:

·         More Windows licenses required (if on a Windows Server)
·         More Virtual Machines to Manage

·         Enhanced Linked Mode with Embedded Platform Services Controllers (Not Recommended)

In this case vCenter is installed win an embedded configuration on the first server.  Subsequent installations are then configured in embedded mode but joined to an existing Single Sign-On domain.

Linking embedded platform services controllers is possible but it is not a recommended configuration.  It is preferred to have an external configuration for the platform services controller. 

The configuration looks like the following:


·         Combination Deployments (Not Recommended)

In this case there is a combination of embedded and external platform services controller architectures.

Linking an embedded platform services controller and an external platform services controller is possible but it is not a recommended configuration.  It is preferred to have an external configuration for the platform services controller. 

As an example, the following depicts one such scenario:


·         Enhanced Linked Mode using only an Embedded Platform Services Controller (Not Recommended)

In this case there is an embedded platform services controller and vCenter Server linked with an external standalone vCenter Server.

Linking a second vCenter Server to an existing embedded vCenter Server and platform services controller is possible but it is not a recommended configuration.  It is preferred to have an external configuration for the platform services controller. 

As an example, the following depicts one such scenario:


Part 2 of this blog post will discuss the different platforms for vCenter, High Availability and different deployment recommendations. 

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