Example Architectural Decision – Single Sign On Configuration for Single Site w/ Multiple vCenter Servers

Problem Statement

What is the most suitable deployment mode for vCenter Single-Sign On (SSO) in an environment where there is a single physical datacenter with multiple vCenter servers?


1. The solution must be a fully supported configuration
2. Meet/Exceed RTO of 4 hours
3. Support Single Pane of glass management
4. Ability to scale for future vCenters and/or datacenters


1. All vCenter instances can access the same Authentication source (Active Directory or OpenLDAP)

2. The average number of authentications per second for each SSO instance is <30 (Configuration Maximum)


1. vCenter servers reside in different network security zones within the datacenter


1. Future proof the environment

Architectural Decision

1. Use “Multi-site” SSO deployment mode

2. Use one SSO instance per vCenter

3. Each SSO instance will reside with the vCenter on a Windows 2008 x64 R2 virtual machine in a vSphere cluster with HA enabled

4. Each SSO instance will use the bundled SQL database

5. (Optional) For greater availability, vCenter Heartbeat can be used to protect each SSO instance along with vCenter and the bundled SSO database

6. The Virtual Machine hosting vCenter/SSO will be 2vCPU and 10GB RAM to support vCenter/SSO/Inventory Service and an additional 2GB RAM to support the bundled SSO Database

7. Using the bundled SSO database ensures only a single vCenter Heartbeat deployment is required to protect each vCenter/SSO instance and reduce Windows licensing


1. To simplify the maintenance/upgrade process for vCenter/SSO as different versions of vCenter cannot co-exist with the same SSO instance

2. If “High Availability” mode is used it would prevent single pane of glass management

3. “High Availability” mode currently requires an SSL load balancer to be configured as well as manual intervention which can be complicated and problematic to implement and support

4. “Basic” mode prevents the use of Linked Mode which will prevent the management of the environment being single pane of glass

5. Where vCenter servers reside in different network security zones, Using Multi-site mode allows each SSO instance to use authentication sources that are as logically close as possible while supporting single pane of glass management. This should provide faster access to authentication services as each SSO instance is configured with Active Directory servers located in the same or logically closest network security zone/s.

6. If one instance SSO goes offline for any reason, it will only impact a single vCenter server. It will not prevent authentication to the other vCenter servers.

7. Reduce the licensing costs for Microsoft Windows 2008 by combining SSO and vCenter roles onto a single OS


1. Use “Basic” Mode, resulting in a standalone version of SSO for each vCenter server with no single pane of glass management

2. Use “High Availability” mode per vCenter

3. Use a shared “High Availability” mode for all vCenters in the datacenter

4. In any SSO configuration, Host the SSO database (per vCenter) on a Oracle OR SQL Server

5. Run SSO on a dedicated Windows 2008 instance with or without the SSO database locally

6. Run a single SSO instance in “Multi-Site” mode , use vCenter Heartbeat to protect SSO (including the database) and share the SSO instance with all vCenters


1. Where SSO is not protected by vCenter Heartbeat (optional), SSO for each vCenter is a Single point of failure where authentication to the affected vCenter will fail

2. “Multi-Site” mode requires the install-able version of SSO, which is Windows Only which prevents the use of the vCenter Server Appliance (VCSA) as it only supports basic mode.

Related Articles

1. vSphere 5.1 Single Sign On (SSO) deployment mode across Active/Active Datacenters

2. vSphere 5.1 Single Sign On (SSO) Architectural Decision Flowchart

3. Disabling Single Sign On – Dont Do It! – Michael Webster (VCDX#66) @vcdxnz001




vSphere 5.1 Single Sign On (SSO) Configuration – Architectural Decision flowchart

The below is the second architectural decision flowchart in my new series and covers a new feature in vSphere 5.1, Single Sign On.

There has been a lot of discussion around “Best Practices” for SSO, I have taken the approach of creating this flowchart with as many scenarios as possible.

I would recommend that you validate any configuration the flowchart results in is suitable for your environment prior to implementing into production.

The flowchart is designed to be used as a guide only, not a definitive decision making resource.

This also compliments some of my previous example architectural decisions which are shown in the related topics section below.

A special thanks to Michael Webster (VCDX#66) @vcdxnz001 & James Wirth (VCDX#83)@JimmyWally81 for their review and contributions to this flowchart.

SSO flowchart V1.0

Related Articles

1. Example Architectural Decision – SSO deployment mode over Active/Active Datacenters

2. vCenter Single Sign-On – Part 1: What is vCenter Single Sign-On?  – By Justin King @vCenterguy

3. vCenter Single Sign-on Part 2 – Deployment options – By Justin King @vCenterguy

4. vCenter Single Sign-on Part 3 – Availability  – By Justin King @vCenterguy

5. vCenter Single SIgn-On – Part 4: Pre Install Requirements – By Justin King @vCenterguy

6. Disabling vSphere 5.1 Single Sign-on – Long White Virtual Clouds – By Michael Webster @vcdxnz001

7. VMware KB: Multisite Single Sign-On deployment best practices

8. Where is the Best Practice Guide for SSO? | VMware Support Insider By 

Example Architectural Decision – Site Recovery Manager Deployment Location

Problem Statement

To ensure Production vSphere environment/s can meet/exceed the required RTOs in the event of a declared site failure and easily perform scheduled DR testing, VMware Site Recovery Manager will be used to automated the failover to the secondary site.

What is the most suitable way to deploy Site Recovery Manager to ensure the environment can be maintained with minimal risk/complexity?


1. Meet/Exceed RTO requirements
2. Ensure solution is fully supported


1. vCenter is considered a Tier 1 application
2. vSphere 5.1
3. SRM 5.1
4. A single Windows instance hosts vCenter, SSO and Inventory services and is protected by vCenter Heartbeat


1. SRM is not protected by vCenter Heartbeat


1. Reduce the complexity for BAU maintenance

Architectural Decision

Install Site Recovery Manager on a dedicated Windows 2008 instance


1. When installing / upgrading /  patching  SRM including Storage Replication Adapters (SRAs) this may require a reboot or troubleshooting which may impact the production vCenter, including SSO and inventory services.

2. Having SRM separate to vCenter ensures the fail over is not unnecessarily delayed in the event of a disaster due to contention with vCenter on the same VM

3. SRM and vCenter work together in the event of an outage, as such they are less complimentary workloads

4. If hosted on vCenter, SRM will then be subject to the same change windows and be impacted during any maintenance performed for applications running on the same OS instance

5. The SRM application has different availability requirements than vCenter, as such if SRM was combined with vCenter, SRM (having a lower availability requirement than vCenter) would have to be treated with the same change management / care as vCenter which would complicate BAU maintenance

6. The SRM service (business) has different maintenance requirements to vCenter, as such they are not suited to be placed on the same VM

7. Having SRM on a dedicated VM aligns with the scaling out recommendation for virtual workloads

8. Having additional components on the same OS increases complexity and may reduce the availability of vCenter


1. Place SRM on the vCenter server


1. One (1) additional Windows 2008 R2 licenses will be required

2. One (1) additional Windows instance will need to be maintained in BAU

I would like to Thank James Wirth VCDX#83 (@jimmywally81) for his contribution to this example architectural decision.

Related Articles

1. VMware Site Recovery Manager, Physical or Virtual machine?

2. Swap file location for SRM protected VMs