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Configure Blob prefixes for analysis

Prefixes are workspace-level Blob Storage configurations that apply across all scopes in the workspace. They aren't specific to the Capacity details feature. Use prefixes to define analysis targets within Blob Storage containers when account-level or container-level aggregation isn't granular enough for your investigation.

Note

Advanced capacity insights are available only in select Azure regions during preview, and coverage can be partial within a listed region. For current coverage, see Regional availability for advanced capacity insights.

Prefixes use the same exact, case-sensitive string-prefix matching semantics as Azure Blob Storage. They define aggregation targets; Storage Discovery doesn't create folders or reorganize blobs.

Prerequisites

Before you configure prefixes, ensure that:

  • The Storage Discovery workspace uses the Standard pricing plan.
  • You have the Contributor or Owner role on the Storage Discovery workspace.

You can observe up to 100 prefixes in a Discovery workspace. Since prefixes are essentially a free-form portion of the blob name, ensure you copy them exactly as they're used in your storage accounts.

Understand prefix format and matching

A configured prefix identifies three logical parts:

Part Description
Storage account The storage account that contains the data.
Container The blob container to analyze.
Prefix The exact string prefix used to match blobs in the container.

The combined value can be represented as:

<storage-account>/<container>/<folder-or-subfolder>

Examples include:

account1/container1/folder1/
account2/container4/
account5/container
account2/container/folder/subfolder2/something.txt

Apply these rules when you define a prefix:

  • Keep the combined configured value between 1 and 1,024 characters.
  • Start the prefix with a letter or number.
  • Preserve the capitalization used in blob names.
  • Escape reserved URL characters correctly.
  • Don't use wildcard, regular-expression, contains, or fuzzy-matching syntax.
  • Characters such as * and ? are treated as literal characters, not wildcards.

Tip

Add a trailing slash when you intend to target a folder-like path. For example, reports/ avoids the broader matches that a prefix such as reports might return.

Add prefixes when you create a workspace

  1. Begin creating a Storage Discovery workspace as described in Create a Storage Discovery workspace.
  2. Select the Standard pricing plan.
  3. Open the prefix configuration step.
  4. Select a storage account and container, and then enter the prefix.
  5. Add any other prefixes that you need, up to the workspace limit.
  6. Complete workspace creation, including the access checks for the workspace roots.

Prefixes are optional. You can create the workspace without configuring one.

Add a prefix to an existing workspace

  1. Open the Storage Discovery workspace in the Azure portal.
  2. Open the workspace prefix-management experience.
  3. Add a prefix.
  4. Select the storage account and container.
  5. Enter the prefix string.
  6. Resolve any syntax validation errors.
  7. Save the prefix.

New prefix aggregations can take up to 48 hours to appear in the Capacity details report.

Edit a prefix

  1. Open the prefix management experience for the workspace.
  2. Select the prefix that you want to change.
  3. Edit the storage account, container, or prefix string as supported by the portal.
  4. Resolve any syntax validation errors.
  5. Review the warning, and then save the change.

Changes can take up to 48 hours to affect aggregation results. During this period, insights for the changed prefix might not be available.

Delete a prefix

  1. Open the prefix management experience for the workspace.
  2. Select the prefix that you want to remove.
  3. Select the delete action.
  4. Review the warning, and then confirm the deletion.

It can take up to 48 hours for the aggregation change to take effect. Storage Discovery doesn't produce new aggregations for a deleted prefix, and the deleted prefix is no longer available for new report analysis.

Analyze a configured prefix

To get prefix-level advanced capacity insights, enable Capacity details after creating the workspace. When data is available:

  1. Open the Storage Discovery workspace.
  2. Select Reports > Capacity details.
  3. Use the Prefix filter to select a configured prefix.
  4. Review the charts for the selected prefix.
  5. Select View resources where available to investigate prefix-level results.

You can use prefix-level aggregations to analyze supported metadata such as capacity, object count, access tier, object age, modification time, last access time, retention, and storage composition.

Understand validation behavior

The portal validates prefix syntax when you create or edit a prefix. Correct errors such as an invalid format or a value that exceeds supported naming limits before you save.

Storage Discovery doesn't continuously validate a prefix after it's saved. If the associated account, container, or blob path changes, the prefix can stop returning data. Review the prefix configuration if a previously populated prefix no longer produces insights.

Behavior when advanced capacity insights are disabled

If you disable Capacity details or change the workspace to the Free plan:

  • Configured prefixes are retained.
  • Prefix aggregation stops.
  • No new prefix-level advanced capacity insights are produced.

If you enable advanced capacity insights again, the saved prefixes can be used when aggregation resumes. You must complete the advanced capacity access checks again.

Next steps

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