Inquiry about Cost Model: Reserved Capacity vs. Pay-as-you-go in Microsoft Fabric

[CReportify]

I am currently using Microsoft Fabric F2 capacity with a pay-as-you-go model. I utilize the capacity for about 10 hours per day and then pause it to save costs. In this setup, I use two notebooks to retrieve data daily and store it in a lakehouse. According to the Fabric Capacity Metrics app, my consumption of CU seconds varies between 4,324 and 33,091. Additionally, I conduct weekly development and testing, which increases my consumption temporarily.

I am now considering switching to a reserved capacity model where I pay a fixed monthly fee. My primary question is:

• Does reserved capacity ensure a truly fixed monthly cost, regardless of my actual usage?
• Are there any exceptions, such as additional costs if I exceed a certain limit or specific types of usage that are not covered by reserved capacity?

Furthermore, I am curious if reserved capacity offers benefits for my use case (daily data consumption, periodic development, and testing) and if there are any limitations I should be aware of.

Kind regards,

Chris

[v-pnaroju-msft]

Hi CReportify,

We have not received a response from you regarding the query and were following up to check if you have found a resolution. If you have identified a solution, we kindly request you to share it with the community, as it may be helpful to others facing a similar issue.

If you find the response helpful, please mark it as the accepted solution and provide kudos, as this will help other members with similar queries.

Best regards,
Pavan

[jennratten]

Reserved capacity pricing can help you manage and reduce costs but it does not guarantee a fixed cost regardless of usage. When you purchase reserved capacity you commit to a specific amount of resources (like compute or storage) for a certian period of time - in return you get a discount compared to pay-as-you-go pricing. If your actual usage exceeds the reserved capacity, you'll be charged at the regular pay-as-you-go rates for the balance.

Certain types of usage, like storage or networking charges are not covered by reserved capacity and will incur additional costs.  Reserved capacity is also typically scoped to specific Azure subscriptions or resource groups, so it might not cover all your usage if you have multiple subscriptions.

Please let me know if I can answer any other questions.

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[CReportify]

Thank you for your earlier response regarding Reserved Capacity. I have a follow-up question to help me assess if Reserved Capacity is the right choice for my workload.

Currently, I use a Microsoft Fabric F2 capacity (pay-as-you-go) for about 10 hours per day, primarily for two notebooks that retrieve data and store it in a lakehouse. According to the Fabric Capacity Metrics app, my daily CU-second usage varies between 4,324 and 33,091, with occasional increases during development and testing phases.

To better understand how Reserved Capacity would work for me, I would like to know:

1. How can I accurately calculate my monthly usage to compare it to the limits of a Reserved F2 capacity?

   • Is it possible to use the Fabric Capacity Metrics app to project this?
   • Are there specific steps or tools you recommend for this calculation?

2. If my usage exceeds the reserved F2 capacity, how are additional costs calculated?

   • For example, would occasional peaks during testing trigger pay-as-you-go charges?
   • Are these costs easy to monitor in real time?

Any guidance or tools that can help me better understand and predict my usage would be greatly appreciated. Thank you in advance for your help!

Kind regards,

Chris

[jennratten · Accepted solution]

Hello - the Azure Pricing Calculator is helpful in terms of estimating different scenarios.  The Total Cost of Ownership Calculator is also helpful.  You wouldn't be able to use the Fabric Capacity Metrics app alone because there are other things like networking and storage which will have costs associated with them that are not tracked by the Fabric Capacity Metrics app.

If usage exceed the reservation then pay-as-you-go charges will apply.  There are many helpful monitoring capabilities included. 

Cost Management + Billing - Microsoft Cost Management | Microsoft Learn 

[gramirez7CR]

Hello @jennratten . Quick question on this "If usage exceed the reservation then pay-as-you-go charges will apply. "  Isn't true that when you choose the reserved instance model, costs are fixed (for capacity), and the worst thing that may happen is throttling, so therere should be no additional costs attached to your monthly bill? Is there any documentation that highlight this about PAYG extra charges for the reservations? Thanks for your support.

[CReportify]

Thanks for the info!