Exchange witness server hardware requirements (Ram, CPU and Hard Drive)

Muhammad Asif
Muhammad Asif used Ask the Experts™
We have two Dell Rx730 PowerEdge servers (256 GB Ram and 14 X 8 TB drives for database and logs) for Exchange 2016. We are going to make a DAG of these two Exchange servers. Is there any specific requirements such as RAM, CPU and Hard Drive for Witness server?
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Nope, just have to comply the regular prerequisites for exchange 2016 and system requirements.


System requirement:

PS: But I think that with just 2 servers you don't use a witness yet, you use a witness server when you have 3 or more.
AmitIT Architect
Distinguished Expert 2017
You can make any server in your Domain as witness server, it could be your file server too. However, make sure it is always available. You need witness server, when you have even number of servers in  your DAG. Remember, 2/3 majority needed for cluster to function. Hope that answers your query.
Muhammad AsifSenior Solutions Architect


Hi Guys,

Thanks for your replies. Please also guide on ReFS with Exchange 2016 server. When I try to create a mailbox-database, the Exchange shows a permissions warning message which is given below with a separate heading. It is also worth mentioning that the databases are created fine in the Exchange but I still need to know the root cause of this warning. Have anyone else have faced the same issue on REFS drives in Exchange 2016.

Error Description:

There was a problem creating directory "D:\Program Files\Microsoft\Exchange Server\V15\Mailbox\REFSDB01" on server "". In order to ensure that the Exchange data is kept secure, please create the directory, if it does not already exist, and configure directory permissions so that "SYSTEM" and the local "Administrators" group have "Full Control" for the folder, subfolders, and files. It is recomended that permission inheritance be broken so that only "SYSTEM" and "Administrators" have access to the directory.
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According to Ross Smith IV, the maximum recommended memory for Exchange is 192GB.

In 2015 it was 96GB, this statement is at the comments to this excellent article. However after September 2017 it's 192GB. Unless you going to run something else on this server together with Exchange, which is not recommended, there's no real need for such amount of memory.

I would personally would prefer four "slower" servers rather than those two.

See here for witness server requirements.

At the bottom of this page, you'll find your answer to the amount and functionality of quorum models.
Muhammad AsifSenior Solutions Architect


I beleive there is not any specific requirements f regarding RAM/CPU etc. for Witness server so it can be created with minimum available resources.
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