Exchange 2019 expands the limit of what is allowable for an Exchange Server in terms of physical hardware/virtual machine requirements. This change applied particularly to memory. Microsoft currently recommends 128GB (Mailbox Role) and 64 GB (Edge Transport) RAM sizes. Maximum memory is capped at 256GB supported as well. Both of these are a significant change from Exchange 2016. The new minimum are probably quite shocking to some Exchange Admins/organizations that are looking to deploy or upgrade to Exchange 2019. Another change was made as well, no longer is there a cap at 32GB, not is there any + 10 MB requirements any more either. For an experience Exchange Consultant, this change is only significant in the fact that it was ingrained that we must always add 10MB to the server’s RAM (in MB) to get the Pagefile size.
The New Pagefile Size Calc
The new requirement from Microsoft on the Pagefile is to size it to 25% of the RAM on the server. If we go by the minimum/maximums for RAM, here are some sample Pagefile sizes:
RAM Pagefile
64GB 16GB
96GB 24GB
128GB 32GB
160GB 40GB
192GB 48GB
256GB 64GB
As you can see, only when we get above 128GB of RAM does the Pagefile surpass the maximum recommended for Exchange 2016. Also we no longer need to add 10MB to the MB number any more. To set this on the server, we can use Set-CimInstance. Below is a very simple set of lines used to remove the old Pagefile and configure a new one of the correct size:
Set-CimInstance -Query “Select * from win32_computersystem” -Property @{automaticmanagedpagefile=”False”}
$RamInMb = (Get-CIMInstance -computername $name -Classname win32_physicalmemory -ErrorAction Stop | measure-object -property capacity -sum).sum/1MB
$ExchangeRAM = $RAMinMb * 0.25
Set-CimInstance -Query “Select * from win32_PageFileSetting” -Property @{InitialSize=$ExchangeRAM;MaximumSize=$ExchangeRAM}
Further Reading
Exchange 2019 System Requirements
Set-CimInstance
