metric details for onelake storage

[Padmanabhan]

I have a cost optimization recommendation idea based on the storage cost.

Identify Unused or orphaned onelake storage,

OneLake charges per GB per month.

Detect workspaces, lakehouses, warehouses, or delta tables with 0 reads for X days but still occupying large GBs.

For this idea which metrics can be used to track the unused storages.

[Padmanabhan]

Hi @V-yubandi-msft 

Thanks for your support. It is clear now.
I have another one doubt.
I extracted the needed metrics of fabric using the powerBI rest API.

"https://api.powerbi.com/v1.0/myorg/groups/{workspace_id}/datasets/{dataset_id}/executeQueries"

But the data is extracted only when the fabric capacity is in resume state. If it is paused the fabric metrics are not get extracted.

Whether we can extract the metrics when the fabric capacity is off ?
Any other ways to extract the metrics when it is paused?

[V-yubandi-msft]

Hi @Padmanabhan ,

Thank you for the update. I'm pleased the previous explanation was helpful.

Regarding your follow up question, this behavior is expected. When Fabric capacity is paused, the semantic model engine is inactive, so APIs that run queries, such as executeQueries, can’t return dataset or capacity metrics.

Currently, there isn’t a supported method to obtain Fabric or dataset level metrics while the capacity is paused. The standard practice is to collect the necessary metrics while the capacity is active and save them externally, such as in a Lakehouse or database, before pausing the capacity to manage costs.

Some metadata APIs may still respond during a pause, but they won’t provide capacity or semantic model metrics.

Thank You.

[Padmanabhan]

Hi @V-yubandi-msft 

Thanks for your guidance.
Can I know about that "Some metadata APIs may still respond during a pause, but they won’t provide capacity or semantic model metrics."

[V-yubandi-msft · Accepted solution]

Thank you for following up. To confirm, there has been no change when a Fabric capacity is paused, the semantic model engine is unavailable, so dataset or capacity metrics cannot be queried via REST APIs.

Currently, there is no workaround to extract these metrics while the capacity is paused.

The recommended method is to collect the necessary metrics while the capacity is running and store them externally before pausing.

If you need access to historical metrics while the capacity is paused, saving them during active periods is the best solution.

[V-yubandi-msft]

Hi @Padmanabhan ,

Everything should be clear now. If you need any additional information, please let me know.

[Padmanabhan]

Hi @V-yubandi-msft 

Where we can check these storage size, usage activity, last read timestamp?

[V-yubandi-msft]

Hi @Padmanabhan ,

Thank you for reaching out to the Microsoft Fabric Community. When looking at cost optimization in OneLake, a few key metrics can help identify unused or orphaned storage.

1. Storage size shows how much space each workspace, lakehouse, warehouse, or delta table is consuming.

2. Last read timestamp captures the most recent time the object was accessed.

3. Read/write activity counts tacks the number of queries or updates over a given period.

4. Workspace activity level reflects overall usage across all assets, while retention shows how long data has been stored without being read.

By combining storage size with usage activity, you can quickly spot large datasets that haven’t been accessed for X days but are still incurring costs. Those become strong candidates for cleanup, archiving, or moving to a cheaper tier.

Helpful reference:
OneLake capacity consumption example - Microsoft Fabric | Microsoft Learn

OneLake consumption - Microsoft Fabric | Microsoft Learn

Regards,
Yugandhar.

[V-yubandi-msft]

Hi @Padmanabhan ,

You can check storage size and usage metrics directly in the Fabric Capacity Metrics app, under the Storage tab.

For activity metrics such as read/write counts and last access timestamps, Fabric offers built‑in usage telemetry and activity logs. For example, warehouses expose query history, while lakehouses and delta tables record access logs. These help you track when data was last used and how often.

FYI:

Regards,

Yugandhar.

[Padmanabhan]

Hi @V-yubandi-msft 

 I can take storage size and usage metrics directly in the Fabric Capacity Metrics app under Storage By Workspaces table.
And in Storage by workspaces and day table has a column "date".
Actually what this date is?
Whether it is the last accessed date of the storage items like lakehouse and warehouses.
And I don't have any idea how to get the last access timestamp for the onelake storage items.

[V-yubandi-msft]

Hi @Padmanabhan ,

Thanks for checking. To clarify, the date column in the Storage by Workspaces and Day table indicates the reporting date for storage usage, showing how much storage was used on that specific day. It does not represent the last accessed date for your lakehouse or warehouse.

The Capacity Metrics app focuses on storage consumption trends, such as current versus billable storage, daily usage, and top workspaces. If you need information on when data was last accessed or usage frequency, please refer to Fabric’s activity logs or telemetry.

Warehouses provide query history, and lakehouses or delta tables have access logs if telemetry is enabled.

Note that OneLake does not display last read timestamps in the Capacity Metrics app.

-Yugandhar.

[Padmanabhan]

Hi @V-yubandi-msft 

Thanks for your assistance.
Whether we can extract these details like warehouses query history and lakehouses access logs using the notebook in that workspace?
Can we connect through microsoft teams?

[V-yubandi-msft]

Hi @Padmanabhan ,

1. It's not possible to access query history or logs directly within a Fabric notebook. These details are available through Fabric’s activity logs and telemetry. If your organization has enabled telemetry export, you can use Log Analytics or Power BI to review the data.

2. Regarding Teams, we don't provide one on one troubleshooting there. Support is offered here in the community or through official Microsoft support channels. For more in depth assistance, submitting a support ticket is recommended.
Create a Fabric and Power BI Support Ticket - Power BI | Microsoft Learn

Thank You.

[Padmanabhan]

Hii @V-yubandi-msft 

Thanks for your support.

Is there any existing recommendation for the orphaned/ unused onelake storage?

[V-yubandi-msft]

Hi @Padmanabhan ,

That’s a good question. Fabric doesn’t automatically highlight orphaned or unused OneLake storage. Typically, you can monitor the Capacity Metrics app and activity logs to identify workspaces or lakehouses with little or no activity.

If you notice inactive items, you can remove them manually. Keep in mind that soft deleted data continues to be billed until it’s permanently deleted, so reviewing retention settings is important. Some teams also export telemetry to Log Analytics or Power BI to generate reports on datasets with minimal usage.

Thank you for your time and for staying involved with the community.

[Padmanabhan]

Hi @V-yubandi-msft 

Whether we can check the "static storage in GB" for individual onelake items like lakehouse,warehouses.
We can take this metric in workspace level.

[V-yubandi-msft]

You’re right. The static storage in GB metric in the Capacity Metrics app is available only at the workspace level, showing the total storage used by the workspace.

Currently, Fabric does not automatically provide storage details for individual items such as lakehouses or warehouses. 

Thank you for your curiosity and engagement.