Questions associated with 2013 to 2019 Exchhange Migration/Upgrade...

Question

I am looking at the following link and am confused by some of the information.
https://learn.microsoft.com/en-us/answers/questions/106570/upgrade-from-exchange-2013-to-exchange-2019.html

Specifically:
2) Make sure, CAS servers are also in the same CU22, as the minimum CU required for coexistence is Exchange 2013 CU21 & above
(What is a CAS Server? I am on exchange2013 CU21...)

3) Install the Exchange 2019 latest CU (Can I install Exchange 2019 latest CU while running 2013 CU 21? , These are on completely separate servers.)

4) Configure the certificates, URL's, connectors (Is there some sort of export tool for certs?)

5) Create a test mailbox in Exchange 2019 and test the client connectivity and mail flow (internal/external/exchange 2013) (I am not sure what this actually means??)

Thanks for any help with the above.
Is there any kind of migration path check list I can follow?
Thanks, B

Answer 1

Hi @BCL

What is a CAS Server? I am on exchange2013 CU21...
CAS server stands for Client Access Server. It is a server role in Exchange.
It can be installed together with the mailbox server role on the same device.

Or you may also install the CAS role on a separate device.
Like in the post, the poster has mailbox servers and CAS servers roles installed on different devices.

While, I suppose that you may have the server roles installed on the same device.
To confirm it, please run the following command via Exchange Management Shell:

get-exchangeserver | fl name,serverrole  

If you can see serverrole Mailbox and ClientAccess on the same server, you don't need to worry about it.
It is supported and recommended to install the roles on the same server.

In addition, only Exchange 2013 or previous versions support a separate installation of the Mailbox server role and the Client Access server role.
In Exchange 2016 and 2019, the Client Access server role is automatically installed as part of the Mailbox server role.

Here is a link on this topic for your reference: Exchange architecture changes

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Can I install Exchange 2019 latest CU while running 2013 CU 21? , These are on completely separate servers.
Yes.
To have Exchange 2013 coexisting with Exchange 2019, you may need to install CU21 or later versions of Exchange 2013.

While, it is always recommended to keep Exchange server updated (install latest CU) since Cumulative Update will fix security and nonsecurity issues in previous CUs.
Due to the recent Hafnium issue, you may need to update to CU23 and install the security update to protect your organization from being attacked.
To install CU23 correctly, please follow the guide in this link: ExchangeUpdateWizard

Note: Currently the CU23 download link is broken, you may download it via this link: https://download.microsoft.com/download/7/F/D/7FDCC96C-26C0-4D49-B5DB-5A8B36935903/Exchange2013-x64-cu23.exe

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Is there some sort of export tool for certs?
You may export the certs via EAC.
Export a certificate : Export a certificate from an Exchange server
Import a certificate: Import or install a certificate on an Exchange server
The links are for Exchange 2019 but work the same way in Exchange 2013.

Or you may also use MMC(Microsoft Management Console) to export/import the certs.
The detailed steps are introduced later in the Exchange Deployment Assistant tool.

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Create a test mailbox in Exchange 2019 and test the client connectivity and mail flow (internal/external/exchange 2013) (I am not sure what this actually means??)
I suppose that Ashok means after you successfully deploy Exchange 2019 server, you may create a mailbox on the new server.
First test whether you can access the mailbox via Outlook or other email clients.
Then test with sending mails from this mailbox to mailboxes which are currently hosted on the Exchange 2013 server and to external recipients to check if there are some problems in the mail flow.

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Is there any kind of migration path check list I can follow?
In conclusion, it is recommended to use Exchange Deployment Assistant tool.
After you input the required information, it will generate the detailed steps and checklist to guide you with the migration.

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