Exchange 2016 Migration planning on phases

When it comes to migration we always need to plan properly before we start the actual project.Study on the the existing messaging environment as a whole and deriving  a detailed analysis is much required.
Study in terms of existing storage, current number of active users,mailbox traffic utilization , load on the exchange servers, email relay on the servers ,email security setup and messaging related components.

This will really help in understanding the current requirement for email platform and therefore we can scale-up the new environment in a healthy way.
Also by doing this study and implementing the new setup can run for another 5 years without any hassles.

In this article we will have a look at some steps which will help in doing an exchange migration in phases for a smooth and successful migration.

Phase 1: Analyzing existing environment :

I have segregated few core components in this phase that can help for better migration.

a) Email Traffic

Analyze the current email traffic flow of the whole environment in terms of monthly, weekly and daily email traffic.
Better to collect 3 sets of data on the above and get the average value on them.
By doing this we can actually plan very well for the new migration in terms of storage and network bandwidth.

b) Active Users

Determine the current number of active users in the environment . If there are mailbox statistics which have been collected on monthly basis in exchange reports it will be better.

By seeing this we can actually analyse the mailbox growth on a monthly basis. This will help us to calculate to some better value in terms of mailbox growth for the organization in the future.

c) Mailbox Growth & Quota

Again analyzing the Mailbox statistics report will give a better result to calculate the mailbox growth of individual users for the next 3 years. We need to calculate them based on the current growth from the time current exchange version is running and depending upon the nature of email traffic. Better to have an overhead value of 50 percent more which will run for a long time without any bottleneck.

Phase 2: Preferred Architecture


Microsoft recommends to have the Exchange servers to be running on physical VM. Since their new architecture is a very good approach which does not require a  very high configuration server ,because they say for future requirement perform a scale out and not scale up( which means bring up an additional mailbox server in future when required and do not scale up the hardware in the initial configuration) which perfectly makes sense.

In any case the Exchange 2016 Calculator needs to be used first to derive the values of your requirement.

Exchange 2016 Calculator

So if you are planning for a physical servers all we need is  a decent server with below configurations minimum.

You can use Commodity server platforms as the PA with the below minimum configuration.

1) 2U, dual socket servers (20-24 cores) according to your requirement choose the cores.
2) Maximum 96GB of memory according to your requirement choose the memory.
3) battery-backed write cache controller
4) 12 or more large form factor drive bays within the server chassis
5) Probably the server with DAS storage.

Virtual (Vmware or Hyper-V):

Though Microsoft recommends the PA to be on the physical server but still the environments running on VMware , Hyper-V have no options if they continue the new provisioning on the VM.

But still if VM is the plan below are the recommendations for  VMWARE:

1) Each new provisioned Mailbox/Edge Server  should have a reserved memory.Exchange Server 2016 calculator results are driven by the expected amount of loads that will be generated based on the actual inputs.

2) Microsoft supports up to 2:1 virtual-to-physical CPU allocation for Exchange Server 2016 in a virtual environment. VMware recommends to leave the cores per socket count at one at all times

3) Storage can be Fiber Channel, iSCSI, and network-attached storage (NAS) shared-storage protocols.

An Example below of how storage can be provisioned for Exchange 2016 VM.

We can use any one of the option Data Stores virtual disks  or RDM Raw Device mappings.


VMware recommends that you set up a minimum of four paths from an ESXi host to a storage array. To accomplish this, the host requires at least two host bus adapter (HBA) ports.

VMFS supports RDM . This  allows a virtual machine to directly access a volume on the physical storage subsystem through Fiber Channel or iSCSI.

The decision to use VMFS or RDM is not dependent on Exchange .So its better to check the backup to ensure it supports the above configuration.

New Improvements in Exchange 2016 have made Exchange 2016 Lower Storage I/O than earlier versions.
But still with a careless planning on storage especially for Exchange will result in a Poor Exchange infrastructure. Concentration on this part is very much required and we need to spend more time on this before building the setup.

4) Network Considerations

Vmware Recommends to use the VMXNET3 network adapter – This  provides better data transmission  with reduced CPU utilization. Better to have single network per site.

From Exchange 2016 since the data is replicated on one network all we need is one NIC card with the above configuration.

Also have Layer 7 load balancing with no session affinity. Also decide your network link and network link latency based on your previous calculated value from the phase 1.

Phase 3: Verify the Exchange Dependent Components Compatibility

After completing the two phases now we need to check the support compatibility of Exchange dependent components.

Below are most of the dependent components

1)   Check your current backup with Exchange and see if it supports Exchange 2016.

2) Check for any Transport categorizer  level Third party software’s compatibility. It can be any Antispam , Antivirus , Signature solutions etc …,

3) Check with existing journaling solution and its compatibility.

4) Check with  existing Archive solution if there is any and see their compatibility.

5) Check with MDM solutions  and its compatibility. There is no more MAPI/CDO support from Exchange 2016 . So you need to make sure that all MAPI/CDO components are retired.

6) Check the current Monitoring solution for Exchange and see if it supports Monitoring Exchange 2016 integration.

Phase 4: Data Center Design 

a) Active Active site : We can go with this option if we have a well connected round trip network latency. By using this option we are utilizing both the sites efficiently. If the data-centers are connected and having a good redundant paths we can choose this option.

b) Active Passive site : Active Passive option is also good but the only part is the DR resources will not be utilized most of the time unless and until there is some issues with the main site unavailability.

For any of the above configuration the preferred architecture is each of the data center should have its own Active Directory Sites.

This is because Safety Net and Shadow Redundancy will work  only when the DAG members are spanned across more than one Active Directory sites.

Phase 5: Deploy & Test the performance

Once above all factors are considered we can go ahead and deploy the Exchange 2016 as per the plan .

In this phase better not to join the servers to the existing infrastructure. We actually need to see if the provisioned servers, storage , networks are strong enough to handle the real load on them.

For that its better to create a dummy domain , not join them on existing domain and test the performance of the provisioned servers by using Exchange Load Generator and Exchange Jet Stress Analyzer.


To check the performance of the disk we can use JetStress Analyzer

Exchange Jet Stress Analyzer

To simulate the end users load we can use Exchange Load Gen Analyzer

Exchange Load Gen Analyzer

Once the loads and performance are tested on the newly provisioned servers we can go ahead and start the coexistence migration.

In the next blog we will discuss on coexistence migration phase.

Hope this helps

Thanks & Regards

Sathish Veerapandian

MVP – Office Servers & Services

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