Automated Disaster Recovery Solution for Microsoft Exchange server using Azure Site Recovery

Summary: This document provides technical guidance for implementing disaster recovery solution for Microsoft Exchange Server using Azure Site Recovery.

Published: April 2015

Applies to: Microsoft Exchange server, Azure Site Recovery

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Automated Disaster Recovery Solution for Microsoft Exchange server using Azure Site Recovery..................................................

Overview.................................................................................................................Exchange server architecture.................................................................................

Large scale deploymentSmall scale deployment

Supported Azure Site Recovery Deployment Options.............................................Prerequisites...........................................................................................................

Enable DR of Exchange application using ASR...............................Protect your Exchange application.........................................................................

Setup AD and DNS replicationEnable protection for Exchange CAS and MBX VMsConfigure Networking

Create a recovery plan...................................................................Perform a Test Failover................................................................Perform an Unplanned Failover....................................................Perform a Planned Failover..........................................................Perform a Failback.......................................................................Best Practices..............................................................................

Capacity planning and readiness assessment......................................................Implementation Checklist.....................................................................................

Summary.....................................................................................Appendix (Scripts)........................................................................

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Automated Disaster Recovery Solution for Microsoft Exchange server using Azure Site RecoveryOverviewMicrosoft Exchange is the preferred software that enterprises use to host their messaging and email services. Exchange ensures communications are also available across PC, phone or browser, while providing unparalleled reliability, manageability and data protection.

Microsoft Exchange natively supports enterprise class high availability and disaster recovery solutions. Database Availability Groups (DAG) which can enable high availability for large scale deployments of Exchange. A DAG can also be extended to a remote site to provide disaster recovery.

Azure Site Recovery1 is an Azure based service that provides disaster recovery capabilities by orchestrating replication, failover and recovery of virtual machines. Azure Site Recovery supports a number of replication technologies to consistently replicate, protect, and seamlessly failover virtual machines and applications to Azure, a secondary private cloud or to a service provider clouds.

Exchange Database availability groups and Azure Site Recovery technologies are complimentary. Exchange DAGs are recommended deployment option to enable best in class disaster recovery for. For small deployments, such as a single server or non-clustered servers, customers can use Azure Site Recovery to protect the servers. Additionally, customers can use ASR recovery plans to orchestrate DAG based failover via scripted actions. Azure Site Recovery based disaster recovery solution has been reviewed by and supported by Exchange.

This document explains in detail about how you can create a disaster recovery solution for your Microsoft Exchange server with Azure Site Recovery, perform a planned/unplanned/test failovers using one-click recovery plan, supported configurations and prerequisites.

Exchange server architecture

Large scale deploymentFor a large scale Exchange deployment, you can use DAGs across two sites and achieve both HA and DR capabilities. A four-member DAG extended across two datacenters provides both datacenters high

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availability and site resilience for the mailbox services and data. This configuration is illustrated in the following figure.

Small scale deploymentA typical small scale Exchange application deployment shown in the picture below has the following key components.

Active Directory – Domain controller to control user access to the exchange application. DNS role would be hosted on the same VM as that of the domain controller. If you have only one domain controller in your environment then you can use any of the replication technologies supported by ASR to replicate the domain controller2.

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Exchange application deployment topology

Exchange – Two VMs with one of the servers hosting a CAS (Client Access Server) role and another one hosting MBX (Mailbox Server) role.

Subnet – Primary side subnet and the recovery side can be different. ASR can recover Exchange on the recovery site even when the subnets on both sides are same, but you would have to ensure that the complete subnet fails over together.

Supported Azure Site Recovery Deployment OptionsCustomers can deploy Exchange server as Virtual Machines running on Hyper-V or VMware or as Physical Servers. Azure Site Recovery can protect both physical and virtual deployments to either a secondary Site or to Azure.

Hyper-V VMware Physical

Site to Site Site to Azure Site to Site Site to Azure Site to Site Site to Azure

Yes Coming Soon Yes Yes Yes Yes

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PrerequisitesImplementing disaster recovery for Exchange application using Azure Site Recovery requires the following pre-requisites completed.

An on-premises Exchange standalone deployment (without using DAG) Azure Site Recovery Services vault has been created in Microsoft Azure subscription3

Enable DR of Exchange application using ASRProtect your Exchange application Each component of the Exchange deployment needs to be protected to enable the complete application replication and recovery. This section covers:

Protection of Active Directory

Protection of CAS and MBX VMs

Networking configuration

Setup AD and DNS replication

Active Directory is required on the DR site for Exchange application to function. There are two recommended choices based on the complexity of the customer’s on-premises environment.

Option 1

If the customer has a small number of applications and a single domain controller for his entire on-premises site and will be failing over the entire site together, then we recommend using ASR-Replication to replicate the DC machine to secondary site (applicable for both Site to Site and Site to Azure)

Option 2

If the customer has a large number of applications and is running an Active Directory forest and will failover few applications at a time, then we recommend setting up an additional domain controller on the DR site (secondary site or in Azure).

Please refer to companion guide4 on making a domain controller available on DR site. For remainder of this document we will assume a DC is available on DR site.

 

Enable protection for Exchange CAS and MBX VMs3 Create Azure Site Recovery vault in Microsoft Azure subscription4 Setting up AD for a DR environment

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Enable protection of CAS and MBX VMs in ASR. Perform relevant Azure Site Recovery configuration based on whether the VMs are deployed on Hyper-V or on VMware.

Recommended Crash consistent frequency to configure is 15minutes.

Configure NetworkingConfigure VM Network SettingsFor the CAS and MBX VMs configure network settings in ASR so that the VM networks get attached to the right DR network after failover.

You can select the VM in the ‘VMM Cloud’ to configure the network settings as shown in the snapshot below.

Configure DNS and Traffic RoutingIf Exchange is available on public internet, then you can setup Azure Traffic Manager to ensure that the traffic is routed to recovery site after failover. For internet facing sites, create an instance of Traffic Manager in the Azure subscription and configure it and your DNS in the following manner.

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Public DNS Public DNS for Exchange sites

Ex: exchange.contoso.com

Traffic Manager

exchange.trafficmanager.net

Public DNS exchangetonprem.contoso.com <Public IP on the on-premises exchange server>

Load balancing method: Failover

Failover Priority list:

1. <URL configured for Primary farm>2. <URL configured for Recovery farm>

Example:

1. exchangepri.contoso.com2. exchangerec.contoso.com

For internal sites, skip Traffic Manager (the above step). Setup an alternate URL other than the name of the VM hosting the CAS and create an alias in DNS for the same using a CNAME record. If the DNS is setup for dynamic DNS updates, then the VMs would register themselves with DNS using the new IP automatically after failover. Else, the DNS entry would have to be updated either manually or using a script post failover5.

The following picture illustrate the network topology of the Exchange application once the complete protection is enable using Azure Site Recovery.

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Network topology for Exchange application with DR

Create a recovery planYou can create a recovery plan in ASR to automate the failover process. Add app tier and web tier in the Recovery Plan. Order them in different groups so that the front-end shutdown before app tier.

Select the ASR vault in your subscription and click on ‘Recovery Plans’ tab. Click on ‘Create’ and specify a name Select the ‘Source’ and ‘Target’. The target can be a secondary site with VMM cloud configured. Select the app tier and web tier VMs to enable protection and click the ✓.

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You can customize the recovery plan for Exchange application by adding various steps as detailed below. The above snapshot shows the complete recovery plan after adding all the steps.

Steps:1. Failover Group 1: Failover the CAS VM

Failover the CAS VM as part of the recovery plan.

2. Failover Group 2: Failover the MBX VMs. Failover the MBX VM as part of the recovery plan.

3. Manual step 3 (optional): Update the DNS records to point to the application at the new site This step is not required

For internet facing sites, no DNS update should be required post failover. Configure Traffic Manager as describes in the previous section and the recovered application will work seamlessly without any manual intervention.

For internal sites, if the DNS is setup for dynamic DNS updates, then the VMs would register themselves with DNS using the new IP automatically after failover.

This step is required

For internal sites, if the DNS is not setup for dynamic DNS updates, the DNS entry would have to be updated either manually or using a script post failover

Refer to Script for updating DNS post failover.

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Perform a Test FailoverRefer to ‘AD DR Solution6’ companion guide for considerations specific to AD during Test Failover. The steps required to do a DNS failover should be done before performing Exchange Test Failover.

1. Go to Azure manage portal and select your Site Recovery vault.2. Click on the recovery plan created for Exchange.3. Click on ‘Test Failover’.4. Select the virtual network to start the test failover process.

5. Once the secondary environment is up, you can perform your validations.6. Once the validations are complete, you can select ‘Validations complete’ and the test failover

environment will be cleaned.

Perform an Unplanned FailoverUnplanned failover (UFO) is executed in the event of a disaster or unexpected outage—an event you cannot plan. UFO incurs some data loss as configured during the protection. UFO ensures that VMs are brought online in Azure immediately. Executing UFO pauses the on-premises VMs.

1. Go to Azure manage portal and select your Site Recovery vault.2. Click on the recovery plan created for Exchange.3. Click on ‘Failover’ and select ‘Unplanned Failover’.

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4. Select the target network and click ✓ to start the failover process.

Perform a Planned Failover1. Go to Azure manage portal and select your Site Recovery vault.2. Click on the recovery plan created for Exchange.3. Click on ‘Failover’ and select ‘Planned Failover’.4. Select the target network and click ✓ to start the failover process.

Perform a Failback1. Go to Azure manage portal and select your Site Recovery vault.2. Click on the recovery plan created for Exchange.3. Click on ‘Failover’ and select planned/unplanned failover.4. Click on ‘Change Direction’.5. Select the appropriate options - data synchronization and VM creation options6. Click ✓ to start the ‘Failback’ process.

Best PracticesCapacity planning and readiness assessment Hyper-V siteUser Capacity planner tool7 to design the server, storage and network infrastructure for your Hyper-V Replica environment.

Azure You can run the Azure Virtual Machine Readiness Assessment tool8 on VMs to ensure that they are compatible with Azure VMs and Azure Site Recovery Services. The Readiness Assessment Tool checks VM configurations and warns when configurations are incompatible with Azure. For example, it issues a warning if a C: drive is larger than 127 GB.

Capacity planning is made up of at least two important components:

Mapping on-premises Hyper-V VMs to Azure VM sizes (such as A6, A7, A8, and A9).

7 Hyper-V Replica Capacity Planner tool8 Azure Virtual Machine Readiness Assessment tool

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Determining the required Internet bandwidth.

Implementation ChecklistStep 1 Create Azure Site Recovery vault in Microsoft Azure subscription.Check the prerequisites to protect your Exchange application.Step 2Hyper-V only step - Download Microsoft Azure Site Recovery Provider, and install it on VMM server / Hyper-V host.VMware only step - Configure Protection server, Configuration server and Master Target servers appropriately.

Step 3Prepare resources.Add an Azure Storage account.Hyper-V only step - Download the Microsoft Azure Recovery Services Agent, and install it on Hyper-V host servers.VMware only step – Make sure the mobility service is installed on all the VMs

Step 4Enable protection for VMs in VMM clouds / Hyper-V sites / VMware sites

Step 5Map resources. Map on premise networks to Azure VNET.

Step 7Create the recovery planPerform test failover using the recovery planEnsure that all VMs have access to required resources, such as Active DirectoryEnsure that network redirections for Exchange application are working

Step 8 Perform DR drill using planned and unplanned failoversEnsure that all VMs have access to required resources, such as Active DirectoryEnsure that network redirections for Exchange application are working

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SummaryUsing Azure Site Recovery, you can create a complete automated disaster recovery plan for your Exchange application. You can initiate the failover within seconds from anywhere in the event of a disruption and get the application up and running in a few minutes from anywhere

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Appendix (Scripts)

Script to update DNS

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