Exchange Server Role Requirements Calculator issues

Exchange Server Role Requirements Calculator.

Hi Folks,

withe the last versions of the Exchange Server Role Requirements Calculator calculating mid Site Exchange Environments with up to 4000 Mailboxes is nearly impossible becaus the Exchange Server Role Requirements Calculator results for number of Mailboxes / Database, Number of Servers and number of DAGs are useless. Very small numbers of Mailboxes per Database, a bunch of Servers and even more than one DAG are not applicablefor such mides Size Environments. What is youre experience und do you even use the tool?
Bernd KruczekAsked:
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AmitIT ArchitectCommented:
I have use this tool several times and it is a good tool. I am not clear about your query. As per my experience, it gives decent result. I tried it for production setup and it gave good result.

Remember, you need multiple tool and testing to come up with right production approach. Designing experience is required to setup any production environment.
Aaron GuilmetteTechnology Solutions ProfessionalCommented:
What settings are you using for mailbox profiles? Resiliency?  Number of database copies?

Use the first tab to select your options.  You need to make sure to modify the number of mailboxes on the first tab, as the default is 80,000 tier 1 mailboxes (as an example).

We have published extensive guidance at
Bernd KruczekAuthor Commented:
Dear Aaron

I use the correct parameters for 450 Mialboxes. But one Mailbox per Database and 8 Servers can't be correct.
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Aaron GuilmetteTechnology Solutions ProfessionalCommented:
How big are the mailboxes (initial and max)?  And the number of active database copies? Lags? And number of storage volumes per server?

For example, I chose 2 active copies, 450 mailboxes with 10GB/50GB limits, and 20 volumes per server (among some other options), and came up with these values:
Exchange Environment Configuration      Value                  Site Resilience Configuration      Value
Exchange Server Version      2016                  Site Resilient Deployment      Yes
Global Catalog Server Architecture      64-bit                  Site Resilience User Distribution Model      Active/Active (Single DAG)
Server Multi-Role Configuration (MBX+CAS)      Yes                  Site Resilience Recovery Point Objective (Hours)      24
Server Role Virtualization      No                  Activation Block Secondary Datacenter Mailbox Servers      No
High Availability Deployment      Yes                  Dedicated Disaster Recovery Mailbox Servers in Secondary Datacenter      No
Mailbox Database Copy Configuration      Value                  Lagged Database Copy Configuration      Value
Total Number of HA Database Copy Instances (Includes Active Copy) within DAG      2                  Lagged Database Copies Hosted on Dedicated Servers      No
Total Number of Lagged Database Copy Instances within DAG      0                  Lagged Copy Log Replay Delay (Hours)      168
Number of HA Database Copy Instances Deployed in Secondary Datacenter      1                  Lagged Copy Log Truncation Delay (Hours)      0
Number of Lagged Database Copy Instances in Secondary Datacenter      0                  Replay Lag Manager Enabled      Yes
                        Replay Lag Max Delay (Hours)      24
Exchange Data Configuration      Value                        
Data Overhead Factor      0%                  Database Configuration      Value
Mailbox Moves / Week Percentage      1%                  Maximum Database Size Configuration      Default
Dedicated Maintenance / Restore Volume?      Yes                  Maximum Database Size (GB)      100
Volume Free Space Percentage      5%                  Automatically Calculate Number of Unique Databases / DAG      Yes
Log Shipping Network Compression      Enabled                  Custom Number of Databases / DAG      0
Log Shipping Compression Percentage      30%                  Calculate Number of Unique Databases / DAG for Symmetrical Distribution      Yes
Exchange I/O Configuration      Value                  Transport Configuration      Value
I/O Overhead Factor      20%                  Message Queue Expiration (Days)      2
Additional I/O Requirement      0.00                  Safety Net Expiration (Days)      8

Tier-1 User Mailbox Configuration      Value
Total Number of Tier-1 User Mailboxes / Environment      450
Projected Mailbox Number Growth Percentage      30%
Total Send/Receive Capability / Mailbox / Day      200 messages
Average Message Size (KB)      75
Initial Mailbox Size (MB)      10240
Mailbox Size Limit (MB)      51200
Personal Archive Mailbox Size Limit (MB)      0
Deleted Item Retention Window (Days)      14
Single Item Recovery      Enabled
Calendar Version Storage      Enabled
Multiplication Factor User Percentage      100%
IOPS Multiplication Factor      1.00
Megacycles Multiplication Factor      1.00
Desktop Search Engines Enabled (for Online Mode Clients)      No
Predict IOPS Value?      Yes
Tier-1 User IOPS / mailbox      0.00
Tier-1 Database Read:Write Ratio      3:2

Datacenter 1 Server Disk Configuration      Disk Capacity      Disk Type
System      4000 GB      7.2K RPM SAS 3.5"
Database + Log      4000 GB      7.2K RPM SAS 3.5"
Log      4000 GB      7.2K RPM SAS 3.5"
Restore Volume      4000 GB      7.2K RPM SAS 3.5"
Datacenter 2 Server Disk Configuration      Disk Capacity      Disk Type
System      4000 GB      7.2K RPM SAS 3.5"
Database + Log      4000 GB      7.2K RPM SAS 3.5"
Log      4000 GB      7.2K RPM SAS 3.5"
Restore Volume      4000 GB      7.2K RPM SAS 3.5"

Server Configuration      Processor Cores / Server      SPECint2006 Rate Value
Primary Datacenter Mailbox Servers      16      60.4
Secondary Datacenter Mailbox Servers      16      60.4
Lagged Copy Servers      16      0

The point being, it's the defacto tool that we use in our internal consulting services for our customers.  I just reviewed settings with another consultant doing a federal deployment last week, and we used this very spreadsheet.

If you're not familiar with this version of the tool, I'd recommend spending time at the product team's blog (, as they discuss what a lot of the values mean.  There were a number of changes made after the 2010 version, as this now includes sizing for CAS roles and a new calculation for megacycles based on the Exchange Performance Sizing guidelines (

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AmitIT ArchitectCommented:
That doesn't sound correct. 1 server is enough for 450 mailbox. It depends what exactly you have provided in the input sheet.
Aaron GuilmetteTechnology Solutions ProfessionalCommented:
Exactly.  The role requirements calculator is based on the requirements you put in.  So, incorrect input = incorrect output.  

If you select "No" to Site-resilient deployment with all of the other options being the same that I selected, you get 4 servers in 1 DAG with 20 volumes.  If you change it to "no" under Highly Available, and modify the sizes of the disk volumes, you can get it to a single server.

In my example, I changed it to 8TB disks and ended up with 201 volumes (2DBs per volume) on a single server (when you choose a non-DAG, non-HA deployment, you need to select the number of servers you want to manage in the numMBXServers). When using DAG deployments, you'll typically want to select the drop down "Yes" for "Automatically determine number of DAGs and Servers."

It's all in understanding how the calculator works and what the "best practices" design goal is.  For example, if you are doing 450 x 50GB mailboxes and want to maintain a certain level of backup / restore ability with low log replay / restore times and account for 30% growth and want to use RAID sets for database volumes and want to have it contained in a single server, you'll need at least 19 disks.

If you change the min/max mailbox sizes to 2GB/10GB, you end up with 13 volumes, 32 mailbox databases, and 9 disks, but you may run into an IOPs constraint depending on how active your users are.

But, then, you end up out of whack for the number of processors and CPU utilization per server, so you may suffer from performance depending on your user profile.  A single server may do it, but you'll have make sure the user mailbox size and usage profiles don't exceed the capability of the server.
Bernd KruczekAuthor Commented:
Hi Aaron,

this is my input and you can see Mailbox Database Copy Configuration is yellow.
Aaron GuilmetteTechnology Solutions ProfessionalCommented:
Based on those configurations (without seeing anything else), you're going to get at least 3 servers.  You have "high availability" selected (which will mean at least 2 servers) and "Site resilient deployment" selected, which means at least one server at each location by default, assuming your network bandwidth is sufficient.  You have "2" selected for "number of HA database copy instances within DAG," which means you need two servers running actively at a minimum (each database can only have one copy per server).  Since you have a "site resilient" deployment, you're going to have a backup of one server in a remote datacenter, which puts you at 3 servers.
Delphineous SilverwingGood Ol' GeekCommented:
No comment has been added to this question in more than 21 days, so it is now classified as abandoned.

I have recommended this question be closed as follows:

-- Aaron Guilmette (https:#a42519326)
-- Aaron Guilmette (https:#a42519468)
-- Aaron Guilmette (https:#a42520499)

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