SCOM Sizing Helper. The most misunderstood Sizing Tool ever.

Microsoft SCOM Sizing Helper Tool which is available at Microsoft Download is one of the core resources of every IT Architect and Consultant who wants to design, implement and size System Center Operations Manager 2012R2, 2016 and 2019.

SCOM Sizing Helper Tool is in reality an excel sheet which is used to calculate the required SCOM Management Servers, ACS Forwarders, Network Devices, Disk requirements for the SCOM Operational and Data Warehouse Databases etc.

The document is for whom, who don’t know anything about the required disk speeds and the number of SCOM Management Servers . The Sizing Helper also mentions on every page “Minimum Hardware Recommendation”. The “Minimum Hardware Recommendation” is in 90% of the cases understood as absolute if the IT Architect or Consultant has no previous experience with SCOM.

Please take a look at Windows Server 2016 System Requirements on Technet. Following information has been mentioned.


  • 512 MB (2 GB for Server with Desktop Experience installation option)

Everyone who has a little bit experience with PCs or Servers will know that it is nearly impossible to run a Server Role on a Windows Server 2016 with 2 GB of RAM.

Exactly the same thing applies to the SCOM Distributed Environment too. With the minimum requirements mentioned inside the Sizing Helper Tool, you will not able to run a healthy environment.

Furthermore in SCOM there is nothing more important than the database disk speeds. If the database disks experiences performance problems the database Queues and SCOM Workflows can get immediately stuck.

If this happens you can get in an endless loop of problems and troubleshooting your SCOM Environment can consume your whole day. Now the question is, how to properly size SCOM and what is the recommended formula ?

How to properly size ?

As an Ex-Microsoft Employee who worked more than on 1000 SCOM cases I have developed the following formula based on my experience.

As you most probably don’t know the SCOM Agent is able to collect and send up to 15MB/s of collected data to the SCOM Management Server. Once the SCOM Management Server receives the data it will forward it directly to the SCOM Operational Database and Data Warehouse Database. Basically the SCOM Management Server acts like a router.

Basically every Agent is able to send up to 15MB in a second in worst case. As an example, if you have 100 Agents in your environment, in worst case your Operational Database would receive 1500MB of data in a second. Based on experience I can say that in most customer environments an average of 7MB/s data is sent.

The formula to calculate the Operational Database Disk Minimum Requirements would then looks like below :
100 Agents x 7MB/s = 700MB Read/Write speed.

700 MB/s would be the minimum without future workload. We have to calculate the future workloads too. If you are planning to add additional 50 servers within the upcoming year I would strongly recommend you to calculate the upcoming Agents with the above formula too.

The formula to calculate the Data Warehouse Database Disk Minimum Requirements looks like below :
100 Agents x The half of what you use above = XXX Read/Write speed.

The reason why we only use the half of the average data transfer speed in Data Warehouse Database is because of financial reasons. Furthermore the Data Warehouse doesn’t need to be so responsive like the Operational Database.

The SCOM Console speed directly depends on the Operational Database speed therefore adding additional disks to the Operational Database disk group would not harm your environment.

Regarding the required SCOM Management Servers and everything else except the mentioned above information you can trust the SCOM Sizing Helper Tool excel sheet and follow the instructions.

Good luck !