Mail migration to office 365 optimizing the mail migration throughput - part 3#4

of 22 | Mail migration to Office 365 | Optimizing the Mail Migration throughput |
Part 3/4
Written by Eyal Doron | o365info.com | Copyright © 2012-2015
Mail migration to Office 365 |
Optimizing the Mail Migration
throughput | Part 3/4
In this article, we review the recommendation and “best practices” that can help us
to improve and optimize the results of the “moving our mail infrastructure to the
cloud” project.
Generally speaking, there are two factors that we can measure:
1. The mail migration throughput – the time it takes to transfer a specific amount
of data to the cloud (Exchange Online).
2. The amount of time required for completion of the mail migration.
For example, in case that the management instructs us to migrate of all the
organization mail infrastructure to the cloud in a period of no more than 10
days, can we accomplish this task?

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In the previous article (Mail migration to Office 365| Factors that impact mail
Migration throughput | Part 2/4) we have to review the factors that impacting the
performance and the result’s (data transfer rate) of the mail migration.
In this article, we review some of these factors and the options that are available to
us for improving and optimize the results of the mail migration throughput or the
time that we will need to accomplish the mail migration project.
Mail migration to Office 365 | Optimizing the Mail Migration
throughput | The article series
The article series includes the following articles:
 Mail migration to Office 365 | Mail Migration methods | Part 1/4
 Mail migration to Office 365 | Factors that impact mail Migration performance
| Part 2/4
 Mail migration to Office 365 | Optimizing the Mail Migration throughput |
Part 3/4
 Mail Migration to Office 365 | Measure and estimate Mail Migration
throughputs | Part 4/4
Factors that impact mail migration throughput
In the following section, we will review some of the factors that impact the
throughputs (transfer rate) of the mail migration and the options that are available

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for use to fine-tune or optimize these factors to improve the results of the mail
migration throughputs.
Network infrastructure
1. Communication line bandwidth
1.1 The “speed” (The bandwidth) of the organizational communication line
To be able to measure the performance of our communication line, we can use a
web tool that is provided by the ISP or use public tools such as speedtest
Using the results, we can get better understanding of the available resources that
we can use such as the Upload rate (when we are moving an organization mailbox
to the cloud, we use the “upload channel), the download rate and so on.
Based on the results that we get, we can decide if there is a need to Increase the
bandwidth of the existing communication line.

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In case that we want to get more detailed information about the load and
performance of the communication line during the day, week, etc.
Most of the ISP can provide this information (for free most of the time), by
accessing a web interface that will display daily, weekly and monthly results of the
communication line performance.
Personally, I like to use a product named: PRTG that enables us to get a very clear
and graphic view of the network performance.
1.2 Working hours and weekends
Office 365 native mail migration tools enable us to schedule the mail migration
process. In case we want to avoid a scenario, in which the mail migration will “load”
the organization communication line (and downgrade the network performance -
the communication lines available bandwidth) or in case that we want to use all the
available communication line bandwidth, we can consider scheduling the mail
migration process to “non-working hours” or implementing the mail migration on
the weekends.
1.3. Network devices performance and tuning
Firewall or Proxy load and performance
To be able to verify that the existing network device such as Firewall or Proxy, are
not the cause for the “Bottleneck” or slowing the performance of the mail
migration, the best practice is to implement a Pilot of mailbox migration and
monitor the load performance of the FirewallProxy to verify that the server
utilization is not high or causing the FirewallProxy to “reach their end limit.
Another important factor that can impact the performance of the mail migration is
configuration settings that restrict the maximum value of the “allowed sessions.”
FirewallProxy | passable restriction of the maximum allowed sessions
Check the FirewallProxy server to verify that the migration process session is not
blocked or restricted by the FirewallProxy policy.
For example, you can read the following article that describes and issue that exists
when using TMG server and performing a mail migration: Office 365 Move Mailbox
fails with transient exception

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1.4. Geographic location of the organization’s network
One of the factors that affect the mail migration throughput to Exchange Online is
the “physical distance” between the organization network and the Office 365 data
centers.
Technically, is not easy to measure or assess the quality of the communication path
from point A (organization network) to the destination (Office 365 data center) but,
the good news is that Microsoft provides a nice Web-based tool named: Office 365
Network Analysis Tool, that can help us to get a detailed information about the
performance of the communication channel between a specific organization
network and the Office 365 data center that hosts the organization mailbox.
The Office 365 Network Analysis Tool is a Java based tool and implemented as a
web application.
To be able to get the required results we will need to choose the suitable URL for
the Office 365 data center that hosts the organization mailbox, specify our Public
domain name that is registered at Office 365 and the tools will start to collect
information and on the next step, display detailed results.
 North America: http://na1-fasttrack.cloudapp.net
 EMEA: http://em1-fasttrack.cloudapp.net
 APAC: http://ap1-fasttrack.cloudapp.net
To be able to use the Office 365 Network Analysis Tool, we will first need to
download and install the java client.
In case that try to use the tool and get the following error “application blocked by a
security setting“, go to the control panel, look for the icon named: Java, and in the
security tab change the default settings to: medium

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In the first screen, we will need to provide the domain name that is hosted in Office
365.

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When the scanning process is completed, we can browse by selecting the different
tabs to get a detailed information about a specific section of the Findings

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When choosing the speed tab, we can see a graph that include information about
the download and the upload speed.

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When choosing the capacity tab, we can get more details about the download and
upload performance.

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1.5. Using a QOS (quality of service) product
Most of the time, the important question is not -“what is the bandwidth of the
communication line”? but instead, “what is the utilization of the communication line
or what is the “free percentage’” of the communication line?.
The process of mail migration considers as demanding because, most of the time
we “transfer” a large amount of data from the organization’s network to the cloud.
In case that your organization uses QOS product, the best practice is to allocate a
predefined percentage of the network bandwidth for the task of the mail migration
or prioritize communication that relates to the mail migration.
1.6. Plan for the required communication line bandwidth
When relating to the concept of “Plan for the required communication line
bandwidth”, one major phase is the bandwidth that is required for the mail
migration (the mailbox data that will be transferred from the Exchange on-Premises
server to the cloud), and additionally, we will need to plan ahead for the required

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communication line bandwidth that will be allocated to the communication
between the organization users who access their Exchange Online mailboxes.
To be able to estimate the required network bandwidth is recommended to use
tools such as: Exchange Client Network Bandwidth Calculator
The Exchange Client Network Bandwidth Calculator is based on excel shit.
On the first screen, we need to provide some general information about our mail
infrastructure.
The second tab will help us to display a clear picture of the requirements that
reacted for the Network bandwidth for each of the different types of mail clients.

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Additional reading
 Exchange Client Network Bandwidth Calculator
 Exchange Client Network Bandwidth Calculator v2
 Plan for Internet bandwidth usage for Office 365
Exchange On-Premise infrastructure
1. Data source (Exchange Server) – Performance
The migration process is going to put a heavy load on the Exchange on-Premises
servers who host the user’s mailboxes or in case that we use hybrid configuration
of the Exchange on-Premises hybrid server.
Before we start the migration process, the best practice is to ensure that the
existing Exchange on-Premises servers have the require resources (RAM, CPU,
Storage, etc.) that will enable this server to perform in an optimal way.

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Q: How can I know if the migration process is overwhelming the Exchange on-
Premises server?
A: Start low as 10 and then increase this number while monitoring the data source
performance to avoid end-user access issues.
In my opinion, the option of “upgrading existing Exchange on-Premises server
hardware” is most relevant in case that the Exchange on-Premises server is based
on a virtual machine because, in this scenario, the hardware upgrade process is a
“one-click procedure.”
Hybrid migration | Server performance
In case that you use a Hybrid server that will use as a “Router” for the mail
migration process, the best practice is to use powerful server-class physical
machines instead of virtual machines for the Exchange 2013 and 2010 hybrid
servers.
Additional reading
 Server Health and Performance
 Understanding Exchange Performance
 Monitoring Mailbox Servers
2. Tuning the MRSProxy resource allocation
The MRSProxy is the Exchange server component that is responsible for
implementing a mailbox move (in our scenario mailbox move from Exchange on-
Premises server to Exchange Online).
The tasks that are executed by the MRSProxy described as: connections.
The default value for the maximum number of connections is 100 but, we have the
ability to “tune” these values based on our needs.
Scenario 1: Exchange server overwhelmed by the migration load
in case that we find that the migration process impairs the performance of the
Exchange on-Premises server, we can reduce the maximum number of connections
that the MRSProxy will be able to use.
Scenario 2: in case that the existing Exchange on-Premises server has sufficient
hardware resources, and we want to expand more resources to the MRSProxy, we

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can increase the default number of connections that will be available for the
MRSProxy and by doing so, optimizer that mailbox migration transfer rate.
The PowerShell command that we can use is:
PowerShell
Set-WebServicesVirtualDirectory -Identity "EWS (Default Web Site)" -
MRSMaxConnections <number between 0 and unlimited; default is 100>
3. Exchange on-Premises server throttling policy
In case that you have an implementation of Exchange on-Premises server throttling
policy, that could slow or “downgrade” the performance of the mail migration
process, consider stopping or disabling these settings while the mail migration is
running.
You can read additional information in the following article: Throttling Policy
Associations in Exchange 2010 SP1
Using Hybrid migration if passable
Using the option of Hybrid migration decreases the amount of data related to mail
migration.
In the previous article (Mail migration to Office 365| Factors that impact mail
Migration throughput | Part 2/4), we describe the difference that exists between
Hybrid migration versus stage migration and Cutover migration regarding the
amount of data that is involved in the mail migration process.
Just a short recap: when using the option of Hybrid migration, we don’t have to
configure a new Outlook mail profile but instead, we can use the same Outlook mail
profile and the existing OST file. By doing so, we are avoiding from the need to
“download back” of the mailbox content to the user desktop.
Note – I’m not familiar with each of the third party mail migration tools that exists
and if there are third party mail migration tools that “know,” how to use the local
Outlook OST instead of downloading all the mailbox data at a new OST file.

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Using the option of: Hybrid migration minimum is based on the minimum
requirements of Exchange 2010 SP3 on-Premises server. In a scenario in which the
organization mail infrastructure is based on older Exchange on-Premises server
such as: 2003, 2007, I would suggest you consider the option of installing a
“temporary Exchange 2010 on-Premises server” for the mail migration project.
The Interesting fact is that you don’t even need to pay for a license. Microsoft
enables an organization that wants to install Exchange 2010 on-Premises server
only as a hybrid server (without using the mailbox rule option) to get a free license
for this server.
Attached a link which leads you to the required license enrolment process:
Self-service Hybrid Edition product key retrieval for customers
Exchange multiple site infrastructure
Mid and large organization will usually have more than one Exchange site.
In case that your organization uses more than one Exchange site (Multiple
Exchange sites) and in case that each of these Exchange sites has a “public
presence” that enables to external hosts to connect the Exchange on-Premises
server who “represent” the Exchange site, we can significantly improve the mail
migration throughputs.
When relating to the subject of mail migration to Office 365 and multiple mailbox
migrations (concurrent mailbox moves), we can use the famous saying “the more
the merrier”
Note – is assumption is correct provided that the mailcommunication line
infrastructure can provide the required resources.
For example, in our scenario, we need to migrate 300 hundred mailboxes from the
organization Exchange on-Premises servers to the cloud.
We have a very narrow time window for completing this task and, we would like to
shorten or to expedite to the process of the mail migration.
In the following diagram, we can see that by using the concept of implementing a
mail migration from a multiple Exchange site at the same time (parallel), we can
multiply or triangles the amount of mailboxes that we can migrate at the same
time.

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Multiple Exchange site’s infrastructure and AutoDiscover
In a scenario of Multiple Exchange site’s infrastructure, we can rely on the
AutoDiscover service for implementing a mail migration from a multiple Exchange
sites at the same time, based on the location of the user mailbox (the Exchange site
and the Exchange server who hosts the user mailbox).
The pre-requirements is that each of the Exchange sites will have a public presence
that includes “Public name” (URL) that can be accessed from a public network.

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To be able to understand better this process let’s use the following example:
An organization named: o365info have two Exchange sites.
One site is located in New York, and additional site is located in Los Angles.
 The Exchange mail server in the New York site uses the following public name:
Mail.Ny-o365info.com
 The Exchange mail server in the Los Angles site uses the following public name:
Mail.La-o365info.com
We are using the option of Hybrid migration, and we are creating a new migration
batch based on a CSV file that includes a list of users whom we want to migrate to
the cloud (Exchange Online). The CSV users list includes a “mixture” of users from
the booth of the organization site.
In our example: User1 and User2 mailboxes are located in the New York site
and User3, andUser4 mailboxes are located in the Los Angeles site.
In our scenario, the AutoDiscover record of o365info.com, is pointing to the
additional Exchange server who is not located on the company site.
When we start the migration batch, Exchange Online uses the AutoDiscover service
for getting the required information about the mail infrastructure etc.
In the following diagram, we can see that Exchange Online ask about the Exchange
server (The CAS server) that can provide information and access to the mailbox
data ofUser1@o365info.com
The origination Exchange server provides an “answer” by redirecting the Exchange
Online to additional server: Mail.Ny-o365info.com
In the second step, Exchange Online will try to connect to the Mail.Ny-
o365info.com and “ask for a permission” to copy the mailbox data of User1.

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Exchange Online creates a new migration endpoint using the connection settings
that were successfully discovered or that you provided manually. We recommend
that you create migration endpoints whose connection settings were automatically
discovered rather than creating endpoints whose settings you entered manually.
This is because the Autodiscover service will be used to connect to each user
mailbox during the migration. If manual settings are used, Exchange Online won’t
use the Autodiscover service, but will connect to a specific source server using the
connection settings you manually entered. If you use manual settings and have
multiple on-premises Exchange servers, you may need to create different migration
endpoints that correspond to each server.
[Data source: Exchange Online Migration Performance and Best Practices ]
Additional reading
 Create Migration Endpoints
 New-MigrationBatch
 Create Migration Endpoints
 How to migrate mailbox data by using the Exchange Admin Center in Office
365

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Office 365Exchange Online factors
1. Office 365Exchange Online Throttling policy
The Throttling policy that relates to mail migration described as: Migration-service
throttling. This policy was designed to limit the maximum migration concurrency.
The good news is that we can easily increase the default value and by doing so,
Increase the number of mailboxes that can be migrated.
In my option, the default value of: “maximum 20 mailboxes at the same time” was
not created to protect the Exchange Online server performance because
theoretically, there is no limitation to the resources that allocated to the Exchange
Online server.
The attention was to protect the Exchange on-Premises server from a scenario of
“overwhelming”. In case that we put too much load on the Exchange on-Premises
server, the load of the migration process, could impact other Exchange on-Premises
server services.
So, in case that you are considered to increase the value of the Migration-service
throttling, please verify that your Exchange on-Premises server, have the required
resources for supporting the amount of mailboxes that will be migrated to
Exchange Online.
After you create a migration batch, you can use the following Windows PowerShell
command to increase this to a maximum of 100.
PowerShell
Set-MigrationEndPoint <Identity> -MaxConcurrentMigrations <value between 1 and
100>
2. The maximum number of concurrent moves for a Migration Endpoints
There is a limit of 100 concurrent migrations for each type of migration endpoint.
For example, your organization could have five Outlook Anywhere migration
endpoints and each endpoint could be configured for 20 maximum concurrent

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migrations. Or you could have two IMAP migration endpoints, with each end point
configured to support 50 maximum concurrent migrations.
[Data source: Create Migration Endpoints ]
In the following screenshot you can see that when we try to use a value bigger than
100
The result is the following error:

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Just a friendly advice: the fact that Office 365 enables us to “extend” the value of a
concurrent mailbox move doesn’t mean that you should automatically use this
option.
A high value of concurrent mailbox moves can overload your network bandwidth
and you Exchange on-Premises servers.
The Number of mailboxes to migrate simultaneously field specifies the number of
connections to your on-premises mail server used during migration. The more

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connections you have to your on-premises mail server, the more mailboxes you can
migrate at one time. While this reduces the amount of time it takes to migrate
mailboxes, these additional connections can consume your Internet bandwidth,
negatively affecting network performance and users’ ability to access Internet
resources.
[Data source: Increase the Number of Mailboxes to Migrate Simultaneously ]
Additional reading
 Maximum Number of Connections to Your Mail Server
 can I create more then one migration end point to speed up the process for
cutover migration

Mail migration to office 365 optimizing the mail migration throughput - part 3#4

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Mail migration to office 365 optimizing the mail migration throughput - part 3#4