Category Archives: HA

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

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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?

Requirements

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

Assumptions

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)

Constraints

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

Motivation

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

Justification

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

Alternatives

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

Implications

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

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

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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 – Datastore Heartbeats for Clusters protected by SRM

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Problem Statement

To enhance the isolation detection abilities of vSphere to minimize the chance of false positive isolation responses  Datastore Heartbeats will be used. What is the most suitable configuration of Datastore Heartbeats for an environment using SRM?

Requirements

1. SRM solution must not be impacted

2. Maximum vSphere environment availability

Assumptions

1. Site Recovery Manager 5.1 protects virtual machines in the cluster/s

2. Appropriate isolation address/es have been configured OR the default isolation address is suitable

3. As all storage is presented via Active/Active storage controllers

4. There are some datastore which are not replicated

5. Isolation response is set to “Shutdown”

Constraints

1. None

Motivation

1. Minimize the chance of a false positive isolation event

2. In the event of isolation, automate the recovery of VMs

Architectural Decision

Use Datastore Heartbeats to enhance the isolation detection capabilities of vSphere.

For each cluster where SRM is used, Configure Datastore Heartbeating to Manually select two non replicated datastores per cluster as the heartbeat datastores

Justification

1. Datastore heartbeating frequently writes to the datastore selected for heartbeating so in the event the network is down, isolation, partition or failure can be properly determained. As a result, during a SRM recovery, datastores need to be un-mounted from the failed site and the Datastore heartbeating may cause one or more datastores to fail to unmount due to I/O on the datastore

2. Datastores failing to un-mount will cause one or more of the SRM recovery steps to report as failed, selecting non replicated datastores prevents this impacting SRM

3. The environment benefits from increases resiliency as a result of datastore heartbeats being used

4. There is no negative impact to the SRM solution

Implications

1. Each cluster will need to have one or more non replicated datastores if Datastore Heartbeating is to be used

2. Additional configuration required to manually select non replicated datastores for heartbeating

Alternatives

1. Do not use Datastore heartbeating

2. Use Datastore Heartbeats and have datastores automatically selected

Relates Articles

1. Example Architectural Decision – Host Isolation Response for FC Based storage