Announcing The Exchange Server 2019 Sizing Calculator

Published May 24 2019 08:03 AM 75.1K Views

The Exchange team is pleased to announce that the Exchange 2019 Sizing Calculator has completed development.  We have heard the community since the release of Exchange Server 2019 and have spent the past few months making usability improvements to the calculator, adding specific investments for Exchange Server 2019 and validating the guidance output by the calculator.  You’ll notice new things have been added and some items that no longer made sense have been removed.  Read on to find out more details on what has changed.

Optimized for Exchange Server 2019

The first thing you’ll likely notice is that the new version of the calculator only supports Exchange Server 2019.  Removing support for previous releases allowed us to streamline the calculator and target today’s usage patterns vs. something that made sense 12 years ago.  Does anyone even remember deploying CCR, LCR and SCR?  You should notice that the input experience is significantly faster.  It also is designed to preferentially provide feedback on the input sheet without having to navigate to other sheets to find out that there is a problem or warning as a result of the specified settings.

Improved Support for Virtualization

Another area that received a lot of attention was providing better guidance when using virtualization technologies.  In particular, you will see new disk types optimized for deployments with Azure if you specify a virtualized deployment.  Choosing one of these disk types will relax rules for the calculator allowing a JBOD configuration to be recommended more frequently.  Using a JBOD configuration allows Exchange DAGs to be deployed more cost effectively with Azure.  This doesn’t change our recommendation that Exchange Native Data Protection offered by DAGs be used in all deployments.  DAGs are still the cornerstone of the Exchange HA/DR story.

You’ll also notice that calculation of CPU requirements is improved for virtualized deployments.  If a virtualized option is chosen, you will see two CPU core values appear.  The first is to specify the number of cores deployed in the virtualization host and the second specifies the number of cores available to the guest virtual machine via the hypervisor.  You’ll also notice that we have added the option to specify Physical CPU:Guest CPU subscription ratio used in system design.  The calculator will use all of these inputs to determine what resources are actually available.  No more fumbling with these calculations on your own.

Updated SPECint Benchmark

Speaking of CPU’s, we also thought it was time to move to a modern benchmark.  The Exchange 2019 Calculator uses SPECint 2017 criteria.  Don’t ask us to translate old CPU ratings to new ones, even SPECint states the standards should be considered separate and distinct with no direct conversion.  End of story.e2019calc_1.jpg

MetaCache (MCDB) Database Support

Once upon a time we considered simply rev’ing the existing calculator to add a single input option and basic calculations to account for the new MCDB feature.  However, what could have been delivered in a matter of minutes to under an hour, we (a nameless individual) decided a more exhaustive refresh of the calculator was warranted.  Queue a lengthy delay and numerous emails asking, “When will the 2019 Calculator be available, Brent?”  MCDB support was in fact the first thing that was added but as you can tell from this post, other work followed.  The MCDB calculations are based upon the same guidance we’ve provided to date, but now most of the math is done for you.  Given the variability of SSD capacities, the calculator will give you a required device count and capacity to be provisioned.  What you procure will vary based upon the values provided and what’s practically available on the market.  Device count should be the overriding determination in how many devices to use.e2019calc_2.jpg

2TB Database Limit

The Exchange Team has always recommended that customers limit database size to 2TB.  Previous versions of the calculator would frequently treat this as a “suggestion” and happily specify larger databases complete with a warning to not exceed 2TB.  That has changed in this updated version of the calculator.  The recommended maximum limit of 2TB for JBOD deployments, and 200GB for RAID deployments will be enforced by default.  Depending upon your configuration, you may see a small increase in the number of DB’s specified by the calculator.  We have worked to make certain that disks are still utilized to the greatest extent possible.  Should you choose to ignore the best advice of the Exchange Team, the calculator will allow you to override the maximum database size, both larger or smaller than what we have chosen by default.

You will notice that this change causes designs to be capacity bound more frequently than IO bound, especially with large mailboxes.  A trend that was already observed in previous versions.  Given the multi-year journey to reduce IO, investments to scale out O365 and now the inclusion of MCDB, it shouldn’t be a surprise that the days of the typical on-premises server being IO bound are in the rear-view mirror.  We think that’s cool, don’t you?


We are excited to release this version of the Exchange Sizing Calculator and hope you find the changes we have made valuable. For the best experience we recommend you use Microsoft Office Professional Plus 2019 or Microsoft Office 365 ProPlus. And now that you are excited as well, and even if you aren’t, you’re probably saying give me the download link already.  Well that’s the last change we are announcing.  The Exchange 2019 Calculator will be included in the DVD .ISO.  So yes, you must wait just a few more days for the release of Cumulative Update 2 before you can take it for a test drive.  Moving this to the .ISO will allow us to update the calculator more readily and more frequently, as well as ensure it is aligned with any future investments in Exchange Server.

The Exchange Team

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Last update:
‎Jul 01 2019 04:36 PM
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