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Example Architectural Decision – Storage I/O Control for Clusters Protected by SRM (Example 2 – Use SIOC)

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Problem Statement

In an environment with one or more clusters with virtual machines protected by SRM, What is the most appropriate configuration of Storage I/O control?

Requirements

1. SRM solution must not be impacted

Assumptions

1. vSphere Version 4.1 or later

2. FC (Block) Based Storage OR NFS (File) based Storage

3. Number of datastores is fairly static

Constraints

1. Storage I/O control can prevent unmounting of datastore during a Recovery which can lead to errors being reported by SRM

Motivation

1. Where possible ensure consistent storage performance for all virtual machines

Architectural Decision

Enable and Configure Storage I/O control for all datastores.

Set the congestion threshold to 20ms

Leave the shares value default

Add a Step to each SRM recovery Plan as Step 1 and Select the Step Placement of “Before selected step”.

Configure step type as “Command of SRM Server” and execute the Scheduled Task which will disable SIOC prior to executing a SRM recovery

Justification

1. The benefits of Storage I/O control can still be achieved without impact to the SRM solution

2. SIOC will not impact SRM failover as it will be disabled automatically as part of the SRM recovery plan

3. In the event the Protected site or is lost, SIOC will not prevent failover

Implications

1. Increased complexity for the SRM solution

2. An additional step to excecute a “Command of SRM Server” is required

3. A Scheduled Task will need to be setup and configured with setting “Allow task to be ran on demand”

4. A script to disable SIOC will need to be prepared and configured with all datastores

Alternatives

1. Enable Storage I/O control and leave default settings

2. Enable storage I/O control and set share values on virtual machines

3. Enable Storage I/O control and set a lower “congestion threshold”

4. Enable Storage I/O control and set a higher “congestion threshold”

5. Disable Storage I/O control

Relates Articles

1. Example Architectural Decision –  Storage I/O Control for Clusters Protected by SRM (Example 2 – Don’t Use SIOC)

 

Example Architectural Decision – Site Recovery Manager Server – Physical or Virtual?

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Problem Statement

To ensure Production vSphere environment/s can meet/exceed the required RTOs in the event of a declared site failure, What is the most suitable way to deploy VMware Site Recovery Manager, on a Physical or Virtual machine?

Requirements

1. Meet/Exceed RTO requirements

2. Ensure solution is fully supported

3. SRM be highly available, or be able to be recovered rapidly to ensure Management / Recovery of the Virtual infrastructure

4. Where possible, reduce the CAPEX and OPEX for the solution

5. Ensure the environment can be easily maintained in BAU

Assumptions

1. Sufficient compute capacity in the Management cluster for an additional VM

2. SRM database is hosted on an SQL server

3. vSphere Cluster (ideally Management cluster)  has N+1 availability

Constraints

1. None

Motivation

1. Reduce CAPEX and OPEX

2. Reduce the complexity of BAU maintenance / upgrades

3. Reduce power / cooling / rackspace usage in datacenter

Architectural Decision

Install Site Recovery Manager on a Virtual machine

Justification

1. Ongoing datacenter costs relating to Power / Cooling and Rackspace are avoided

2. Placing Site Recovery Management on a Virtual machine ensures the application benefits from the availability, load balancing, and fault resilience capabilities provided by vSphere

3. The CAPEX of a virtual machine is lower than a physical system especially when taking into consideration network/storage connectivity for the additional hardware where a physical server was used

4. The OPEX of a virtual machine is lower than a physical system due to no hardware maintenance, minimal/no additional power usage , and no cooling costs

3. Improved scale-ability and the ability to dynamically add additional resources (where required) assuming increased resource consumption by the VM. Note: The guest operating system must support Hot Add / Hot Plug and be enabled while the VM is shutdown. Where these features are not supported, virtual hardware can be added with a short outage.

4. Improved manageability as the VMware abstraction layer makes day to day tasks such as backup/recovery easier

5. Ability to non-disruptively migrate to new hardware where EVC is configured in compatible mode and enabled between hosts within a vSphere data center

Alternatives

1. Place SRM on a physical server

Implications

1. For some storage arrays, the SRM server needs to have access to admin LUNs and using a virtual machine may increase complexity by the requirement for RDMs

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

Related Articles

1. Site Recovery Manager Deployment Location

2. Swap file location for SRM protected VMs

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Example Architectural Decision – Site Recovery Manager Deployment Location

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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?

Requirements

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

Assumptions

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

Constraints

1. SRM is not protected by vCenter Heartbeat

Motivation

1. Reduce the complexity for BAU maintenance

Architectural Decision

Install Site Recovery Manager on a dedicated Windows 2008 instance

Justification

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

Alternatives

1. Place SRM on the vCenter server

Implications

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

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