Use large cases in Advanced eDiscovery (preview)

More organizations are using the Advanced eDiscovery solution in Microsoft 365 for critical eDiscovery processes. This includes responding to regulatory requests, investigations, and litigation. As usage of Advanced eDiscovery increases, a common customer requirement is to expand the total amount of content that can be managed in a single Advanced eDiscovery case. To help accommodate significant increases in case size, both for total data volume and the total number of items, you can now choose a large case format when you create an Advanced eDiscovery case.

Create a large case

To create a large case:

  1. Go to and sign in.

  2. In the left navigation pane of the Microsoft 365 compliance center, click eDiscovery > Advanced.

  3. On the Advanced eDiscovery page, click the Cases tab, and then click Create a case.

    The New eDiscovery case flyout page is displayed. The Case format section provides the option to create a large case. Choose this case type if you need to collect a large amount of content in a short period of time.

    Large case option on the New eDiscovery case page.

  4. After naming the case, select the Large case option, and then click Save to create the large case.

Benefits of large cases

The new large case format allows you to manage cases that contain over 40 million items. This capability helps you effectively manage large volumes of case data through the entire eDiscovery workflow.

Here's a list of other benefits of large cases in Advanced eDiscovery workflow.

  • Collection: In the large case format, you can collect up to 1 TB of data for a single collection.

    For each large case, the collection settings will default to collect Cloud Attachments and contextual Teams and Yammer content. These settings help to collect the full picture of digital communications within an investigation. For Teams and Yammer contextual conversations, the large case format will convert time-based snapshots of 1:1, 1: N and Channel conversations into html transcripts to help provide context of conversations and reduce total number of items produced by chat-based content.

  • Review: Each review set will support up to 1 TB of pre-expansion content. Additional metadata will be available for filters and queries including Team name, channel name and conversation name for Teams content. Each transcript will include time-based content for before and after the responsive item. For Channel conversations, the root post and all replies will be collected for responsive content.

  • Export: You can export large sets of content in a single export job. The large case format lets you can export 5 million documents or 500 GB, whichever is smaller in an export job.

Additionally, the new large case format includes an updated user interface that displays the total size of each review set in the case. Review set sizes are displayed in a column on the Review sets tab and in a flyout pane that persists of every tab in the case.

Large case statistics in Advanced eDiscovery user interface.

Known issues

  • The option to export content as Loose files and PSTs is not currently supported in large cases (the option is greyed out). This export option for large cases will be supported soon. For more information about exporting content, see Export documents from a review set in Advanced eDiscovery.

  • The Advanced indexing that occurs when you add custodians and non-custodial data source to a case is not currently supported in large cases. The indexing job is created, but it doesn't complete. Advanced indexing in large cases will be supported soon. For more information about Advanced indexing, see Advanced indexing of custodian data.

Frequently asked questions

If I attempt to collect over 1 TB in a single collection, will it work?

The performance will be negatively impacted and may cause instability in some instances.

If cloud attachments are included by default in the large case format; how can I remove that content from my review experience?

Use review set filters to filter by message kind or to exclude cloud attachments by using the HasAttachment filter. For more information, see Query and filter content in a review set.

When exporting chat conversation transcripts, will the load file contain all of the expanded metadata and a single item for each transcript?

All metadata for a conversation is embedded in the HTML transcript file. Many of the common fields are available in the load file. For more information about exported metadata, see Document metadata fields in Advanced eDiscovery.