Mail Migration to Office 365 | Measure and estimate Mail Migration throughputs | Part 4/4

In this article, we review the subject of mail migration throughputs when migrating existing mail infrastructure to Office 365.
We need the answer for the for the mail migration throughputs for a couple of reasons:

Reason 1: in a mail migration project, we need to provide a due date for the completion of the migration process.

Reason 2: when implementing the mail migration, we need to have some baseline or a reference that could help us to understand if the existing results of the mail migration throughputs are reasonable or in case that we notice that the mail migration throughputs is very low, find the reasons for the “Low throughputs” and passable solution that will help us to optimize and improve the throughputs (Transfer rate) of the mailbox content to the cloud.

A quick reference for the article series

	Office 365 Mail migration | Migration methods | Part 1/4 The first article on this series includes a description of the different mail migration options that are available for us for migrating existing mail infrastructure to Office 365 (Exchange Online) and focus on the features and the characters of the different mail migration methods that relate to the mail migration.
	Mail migration to Office 365| Factors that impact mail Migration throughput | Part 2/4 The second article includes a review the different factors that impact the performance of the mail migration throughput.
	Mail migration to Office 365| Optimizing the Mail Migration throughput | Part 3/4 The third article recommendation and best practices for improving and optimize the performance of the mail migration throughput.

Mail migration to Office 365 common questions that need to be answered

One of the first questions that we could ask is: what is the required time for migrating a mailbox to the cloud?

The next question could be: what is the exact definition of a standard mailbox?
(A user mailbox could be 1GB mailbox or 20GB with hundreds of thousand mail items).

Let’s assume that we can define the size of an “average or standard mailbox.” We still need to know, how much time it will take to migrate all the organization mailboxes to the cloud or in other words, what is the expected or the average transfer rate when migrating mailboxes to Exchange Online?

Let’s assume that we have implemented some pilot, migrate 10 mailboxes to Exchange Online, measure the average transfer rate and come off with some numeric results.

The question now is: does this result consider as bad? Average? Good? Do we have some guideline for the expected transfer rate result?

Mail migration to Office 365 | Performance of different migration methods

In the following section, we will try to provide some estimation for the expected mail migration throughput based on the Microsoft article: Exchange Online Migration Performance and Best Practices

In the following screenshot, we can see a data table named: “Performance for migration methods.”

Before we start to analyze the information on the table a couple of notes:

• Many of the important details appear in the “note section” under the table.
• The information in table includes some “holes” because the measurement and the results that appear in the table (and in the note section) relate to different values of concurrent mailbox’s migration. For example, the mail migration throughputs for Cutover and Stage migration relate to 100 concurrency versus the throughput’s results of Hybrid migration that relate to 20 concurrency.

To be able to display the data more clearly I have created the following table:

General conclusions from the “Performance for migration methods”.

1. MAPI\RPC mail migration versus EWS method

As it was mentioned in the former article (Mail migration to Office 365| Optimizing the Mail Migration throughput | Part 3/4 ) ,when we perform mail migration from Exchange on-Premises server, we can “address” the Exchange on-Premises server in two ways: MAPIRPC or EWS.

By looking at the data, it is very clear that when we perform the mail migration by addressing the Exchange EWS “listeners” that mail migration throughput are much better.
For example: Cutover and Stage mail migration is implemented by using MAPI/RPC connection to the Exchange on-Premises server verse’s Hybrid Migration that addresses the EWS “listener.” We can see that the results for 100 concurrency mailbox migration are very different when we compare the Cutover and Stage mail migration versus the Hybrid mail migration: the results range for Cutover and Stage mail migration for 100 concurrency is: 10-15GB and the results of Hybrid mail migration are: 20-50GB.

2. Single mailbox migration versus multiple mailbox migration

Another interesting information that appears in the data table relates to a scenario of: Single mailbox migration versus multiple mailbox migrations.

In the following screenshot, I have highlighted the information the estimated throughput of Single mailbox migration versus multiple mailbox migrations when we use the option of Hybrid migration. Clearly the throughput results of Single mailbox migration are inferior versus the throughput results when we perform multiple mailbox migrations.

The reason for this difference

I try to understand what the reason for this difference is. The article includes the following note:

Observed single mailbox move throughput is in the 0.3–1.0 GB/hour range. More concurrent mailbox migrations can be used to achieve higher data migration rates. For example, with 50 concurrent moves, the overall throughput will be in the 15–50 GB/hour range. Single mailbox move throughput will slow down when the on-premises CAS (MRSProxy) server is at hardware capacity. Consider adding more servers to increase migration velocity

It’s not clear to me if this note relates to a scenario of performing multiple mailbox migrations from multiple Exchange on-Premises server or performing multiple mailbox migrations from a single Exchange on-Premises server, but the general conclusion is that we will get much better results when we implement multiple mailbox migrations.

3. Hybrid mail migration versus Third party EWS Migration

The preferred method for performing mail migration in Exchange based environment is addressing the EWS services of the Exchange server.
The data in the table include information about EWS mail migration that is performed by using the Hybrid migration versus Third party EWS Migration. The conclusion from the results is that Hybrid migration provides a better throughputs result, then Third party EWS Migration tools.

Calculating the throughput for the mail migration

In the following section, we will try to “translate” the data in the “Performance for migration methods” table (Exchange Online Migration Performance and Best Practices ) to time units.

Range of values
Let’s start with the concept of: “Range of values.” For example: the information in the “Performance for migration methods” table says that when using the option of Hybrid configuration with 20 concurrency (multiple mailbox migration) the throughput could be a value starting from 10GB per hour and ending with 20GB per hour.

The reason for using a range of values instead of proving a “single number” is that there are many possible factors (which we review in the article: Mail migration to Office 365| Factors that impact mail Migration throughput | Part 2/4) that can impact the mail migration process and by doing so, provide different results.

Although it is not literally written in the Microsoft article, I assume that the “numbers” that appears in the data table are some kind of average that was created from analyzing the data (the results) from many “cloud mail migration projects.”

For simplifying the use of the data range, I have created the following diagram.
In the “low range” we get a mail migration throughput of 10GB per hour, in the “High range” we get a mail migration throughput of 15GB per hour, and additionally, I have added a “Mid-range” that is collocated as the “Half Way” between the Low range and the High range. In our scenario, the “Mid-range” mail migration throughput of 12.5GB per hour.

Q1: Can we use these values\number as an absolute number when we need to provide an estimation for the mail migration throughput?

A1: My opinion is that we cannot relate to this numbers as an “absolute asset value” because these results are based on averages. In the reality, our infrastructure could lead to much worse results or, in a “best-case scenario” case scenario” provided that our organization has unlimited resources or all of our infrastructure is “perfect,” theoretically we can get better results.

Calculating the time for a mail migration

Scenario 1: Hybrid migration | Single Mailbox Move| Data transfer rate: GB per Hour

The information in the “Performance for migration methods” table says that when using the option of Hybrid configuration for a single mailbox migration, the throughput could be a value starting from 0.3GB per hour and ending with 1GB per hour.

It is quite easy to understand that the estimated throughput of a single mailbox migration is “Inferior” verses the throughput that we achieve when implementing multiple mailbox moves.

If we use a graph for drawing the range, we will get the following graph:

In case that we want to provide an estimate for the time that we need for migration a single 10GB mailbox, the worst-case scenario transfer rate (Low range) is: 32.7~ hours and in the best-case scenario (High range), that time which is required to migrate the mailbox to Exchange Online is:10~ hours.

Hybrid migration | Single Mailbox Move | time range calculation

To make the information more “real”, I have created the following table that includes three optional scenarios for a single mailbox move:

What is the calculation formal that we use?

If you are interested in the way that I have to use to calculate these values, the formula is very simple.

For example: the article says, “Observed single mailbox move throughput is in the 0.3–1.0 GB/hour range”.  To be able to calculate the time that will take to migrate 2GB Mailbox using the “Low range” option, we use the following formula.

1GB = 1,024 Megabytes
2GB = 2,048 Megabytes

The “Low range” transfer rate is 300 Megabytes per hour (or if we want to be more precise the number is 306 Megabytes because that article present data that is measured in Gigabytes)

So the formula will be: 2,048/306 = 6.69
is simple words, in case that we want to relate to the Low-range transfer rate in will take six and a half hours to move a Mailbox size of 2GB to the cloud.

Scenario 2: Hybrid migration | Multiple Mailbox Move| Data transfer rate: GB per Hour

In the following chart, we can see the presentation of the information about the transfer rate. The Low-range value is: 10GB, meaning that when we migrate multiple mailboxes to the cloud the worst-case scenario is based on the transfer rate of 10 Gigabytes per hour, the “Mid-range” (the article doesn’t provide a mid-range. I have used the value by calculating the “half-way between the way between the low end value and the High end value) enable us to move of 10 Gigabytes per hour to the cloud in the best-case scenario; we can expect to move of 15 Gigabytes per hour of mailbox data to the cloud.

Example table: hybrid migration Multiple mailbox move (20 mailboxes).

In this example, the calculation is based on the assumption that we use Hybrid migration for migrating 20 mailboxes at the same time.

In this scenario, we add additional variables to the calculation formula because when we deal with a “group of mailboxes” first, we need to define some estimation of the average size of each of the mailboxes and second, we need to calculate the total amount of the data that will be “transferred.” For example, if we want to migrate 20 mailboxes when the average size of each of the mailboxes is 2GB, the total amount of data that will be transferred is: 40 Gigabytes.

For example: in a scenario in which we use Hybrid migration and implement multiple mailbox migrations for mailbox with an average size of 5GB, the time estimation for the compilation of the migration could be as follows:

• Low range scenario: 10.2~ hours
• Mid-range scenario: 8.2~ hours
• High range scenario: 6.8~ hours

Hybrid migration | Multiple Mailbox Move | 20 concurrency

The following table includes estimation of the average time that will take to migrate Exchange on-Premises server mailbox to Exchange Online when we use a migration batch that migrate 20 mailboxes (20 concurrency).

Mailbox migration to Office 365 calculator

Based on the data in the “Performance for migration methods” table (Exchange Online Migration Performance and Best Practices  )

I have created an Excel based calculator who will help you to get a general estimation about the time that it will take to migrate existing mail infrastructure to Exchange Online.

The “results” are different when using single mailbox migration versus multiple mailbox migrations, when using different methods of mail migration and when we use a different number of the concurrent mailbox moves.

How to use the Office 365 mail migration calculator

In the following screenshot, we can see an example to the Office 365 mail migration calculator when we use a scenario of Hybrid migration of multiple mailboxes (20 concurrent moves).

We will need to provide the average size of the mailbox (Number 1) and the number of the mailboxes that will be migrated (Number 2).
After we enter the required information, we can see the total amount of data that we are going to migrate. In our example, 20 mailboxes with average size of 10,000 MB will create a total of 195 GB (Number 3).

The result defines a time range of passable results (Number 4).
For example, in case that our infrastructure is not optimized or overloaded, the time that it will take to migrate 20 mailboxes (each mailbox size is 10GB) is: 19.5 hours.
In case that we have “best-case scenario,” case scenario”, the time that it will take to migrate 20 mailboxes is: 13 hours.

Single Mailbox Migration throughput calculator

Instructions: Enter the value of the mailbox size in MB in the green field and, the result would then be provided a light blue field.
This may take a few seconds to load.
You may also want to view the full-size “Multiple and Single Mailbox Migration throughput calculator” workbook.

Multiple Mailbox Migration throughput calculator

Instructions: Enter the value of the average mailbox size in MB in the green filed + the number of mailbox that will be migrated and, the result would then be provided a light blue field.
This may take a few seconds to load.
You may also want to view the full-size “Multiple and Single Mailbox Migration throughput calculator” workbook.

A quick reference for the article series

	Office 365 Mail migration | Migration methods | Part 1/4 The first article on this series includes a description of the different mail migration options that are available for us for migrating existing mail infrastructure to Office 365 (Exchange Online) and focus on the features and the characters of the different mail migration methods that relate to the mail migration.
	Mail migration to Office 365| Factors that impact mail Migration throughput | Part 2/4 The second article includes a review the different factors that impact the performance of the mail migration throughput.
	Mail migration to Office 365| Optimizing the Mail Migration throughput | Part 3/4 The third article recommendation and best practices for improving and optimize the performance of the mail migration throughput.