Issue

The migration of data Migrating data from Google Vault to the Microsoft 365 Purview environment while ensuring ensuring no data loss and maintaining the same functional capabilities previously guaranteed by Google Vault (supported by with the copmlement of Exterro).

This is due to the decommissioning of Google services and Google Vault in order to leverage the capabilities of Microsoft 365.

Recommendation

Option 3: Extract Google Vault data to a secure repository (GCP) + use Purview for active & new legal holds + retire Exterro

Background & Context

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Historically, the legal and compliance departments have relied on a combination of Google Vault for native data retention and Exterro as the primary orchestration layer for managing legal holds and complex discovery workflows. However, as part of the broader infrastructure modernization and per the directive from the CISO Office, the Exterro platform is being phased out alongside Google services.

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For data move please refer to article LM01_KDD021 - GAM to support migration (GVault / Deleted Users / Talarian): https://wiki.syensqo.com/x/iDIzOg

Current Deleted users Ownership reassignment process

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Coexistence Period

During the migration from Google Workspace to Microsoft 365, "Legal Hold Subjects" will be managed in a split-governance model to ensure no data is lost during the transition.

The Strategy

• Microsoft Purview: Governs migrated Mailboxes and OneDrive (formerly MyDrive) files. Holds are applied here immediately upon migration.

  • Will hold data for new holds on active users right after the migration
  • Will hold data  for new holds on users leaving the company right after the migration.
  • Will hold data for sensitive users right after the migration as per data retention policy.

• Google Vault: Governs Google Chat and any legacy data not yet decommissioned. Users must remain on hold in Vault until Google services are fully disabled.

  • Stores data for active users under litigation.
  • Stores deleted data for users under litigation.
  • Stores data for "Archived users" who left the company.

During the coexistence:

• The new casses and sensitive users being migrated to Microsoft will be covered by Purview.
• The ongoing holds will be stays in GVault for archived users, and for active users deleted data.

Deleted User Data: GCP Cold Storage

To reduce licensing costs while maintaining compliance, data for deleted users will be transfered to a Google Cloud Platform (GCP).

1. For archived users, before a Google account is deleted, OR for Active users on hold (litigation or with sensitive role) a full export of Vault data is performed.

   1. This data is moved to a GCP Archive bucket.

      1. Retention:

         1. All exported data are on hold during the active litigation case, until it ends.

         2. All exported data after sensitive role departure, or litigation case is over, are subject to a strict 5-year retention policy to meet regulatory requirements.

         3. After 5 years, the GCP lifecycle policy will automatically purge the data unless a manual legal extension is applied.

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GVault to Purview use cases

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Operational Impact:

Storing deleted users' data in GCP while retaining new information in Microsoft 365 creates a fragmented discovery environment, complicating workflows for the Legal team.

Assumptions

• Secure Staging: The Internal VM GCP storage will serve as a secure, high-capacity staging area where data integrity (hashing) is verified before ingestion into M365.

• Chain of Custody: The migration process will preserve all essential metadata (creation dates, authors, recipients) to ensure the data remains legally defensible.

• Tooling & Connectivity: The VM will be equipped with necessary migration tools and sufficient network bandwidth to handle large-scale data transfers between Google and Microsoft.

• Formatting Parity: Google-native files (Docs, Sheets) will be successfully converted to Microsoft-compatible formats during the VM staging phase to allow for full indexing by Purview.

• Capacity: The destination Microsoft 365 environment has been provisioned with adequate storage to accommodate the total volume of legacy data from Google Vault.

Constraints

• Migration from GVault to Microsoft Purview is not supported, while the metadata are lost.
• Migrating Data from GVault into Microsoft purview without metadata are not exploitable.
• Migration of data from Gvault will be a process that may take up to 4–5 weeks.
• The migration can start only after the project completes the “Coexistence” phase. Users under legal hold must no longer be able to continue using GWS, because for the migration a set of closed/static data is required. 
• During coexistence, data keeps changing/being overwritten, which prevents the migration.
• Migration timeline should be set to early October 2026.

Impacts

• Lower long-term risk through structured migration: Moving Google Vault data to a secured repository and then closing Vault can simplify the legacy footprint—provided holds/retention and chain-of-custody documentation are recreated—making compliance posture clearer over time.
• Exported Vault data may be harder to search/use in Purview (format/metadata/indexing gaps)
• Manageable change with short transition phase: Expect a temporary ramp-up (training, updated procedures, initial validation), but day-to-day operations should stabilize quickly once Purview processes and access to legacy data are validated.

Retention Policy

Options considered

Option 1: Maintain Google Vault for legacy data + Purview for new cases + Exterro (notifications only)

• keep Google Vault for legacy Google data (need to license all existing vaulted users active and inactive ~2200 x7$/user = 15400 yearly)
• Purview eDiscovery for new litigation on M365 : covered by E5 / F5 addon
• reduce Exterro scope for litigation notification only (missing in eDiecovery) : cost to be defined

Option 2: Extract Google Vault data to secure repository (GCP) + Purview for new cases + Exterro (notifications only) 

• Extract GVault data into a secured place (to be defined) today using GCP project
• New Microsoft Purview (eDiscovery) for new litigation: covered by E5 / F5
• reduce Reduce Exterro scope for litigation notification only (missing in eDiecovery): cost to be defined

Option 3: Extract Google Vault data to secure repository (GCP) + Purview for new cases + retire Exterro

• Extract GVault data into a secured place (to be defined) today using GCP project
• New Microsoft Purview (eDiscovery) for ongoing active users & new litigation: covered by E5 / F5
• Stop Exterro and find a new tool

Option 1 - Keep Vault and Exterro 

Option 2 - Keep Vault and Exterro

Option 1 - Keep Vault and Exterro

• utilize (eDiscovery) functionality

Evaluation

The shift to Purview reduces architectural complexity and licensing costs, but moves the organization from a specialized "Legal-First" tool (Exterro) to a "Platform-First" tool.

The primary trade-off is the loss of Exterro’s robust Legal Hold Notification automation, which now requires a defined internal process within the Microsoft environment.

See also

The following section describes relevant documentation:

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