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Records Authority
Category: E-Discovery and Legal Holds

Preservation Hold Library

Also known as: PHL, Preservation Hold library
Simply put

The Preservation Hold Library is a hidden storage area that Microsoft SharePoint and OneDrive create automatically when a retention policy, retention label, or legal hold applies to a site. When a user edits or deletes content that is subject to such a rule, a copy is moved into this library so it is not permanently lost before any required retention period ends. It is a system location and is generally not intended for interactive, day-to-day use.

Formal definition

The Preservation Hold Library is a hidden system document library that SharePoint and OneDrive provision automatically on sites where a retention policy, retention label, or legal hold has been applied (for example via a site policy or organization-wide retention configuration). It functions to preserve content that would otherwise be modified or deleted: when an in-scope item is changed or removed, a copy is captured and retained in the library to satisfy the applicable retention or hold requirement, rather than being immediately purged. Practitioners should note that this is a platform-specific mechanism within the Microsoft ecosystem for enforcing retention and preservation obligations; it addresses preservation of copies for disposition control and is distinct from broader records classification, archival transfer, or the designation of an authoritative record. Access is typically restricted, and its behavior depends on the specific retention configuration and organizational policy in force.

Why it matters

The Preservation Hold Library addresses a persistent tension in collaborative platforms: users routinely edit and delete content in the ordinary course of work, yet retention and legal hold obligations may require that certain content be preserved regardless of user action. By automatically capturing copies of in-scope items before they are permanently purged, the mechanism helps organizations avoid the inadvertent loss of content that must be retained for compliance, evidentiary, or business reasons. For records and information governance professionals, this makes the feature a practical control point where retention policy is actually enforced within the Microsoft ecosystem, rather than merely declared.

Because the library operates automatically and is generally hidden from everyday view, its behavior is frequently misunderstood. Users and administrators sometimes discover that storage continues to be consumed by content they believed was deleted, or that items appear to be inaccessible or "stuck" until the applicable retention period or hold is resolved. Understanding that this is expected behavior, a preservation function tied to a specific retention configuration or legal hold, is important for setting accurate expectations, planning storage, and responding to user queries about content that cannot be immediately removed.

Professionals should be careful not to overstate what the Preservation Hold Library represents. It preserves copies of content to support disposition control and hold requirements; it is not, in itself, a records classification scheme, an archival transfer process, or a designation of the authoritative record. Treating it as equivalent to a formal recordkeeping repository can lead to gaps in governance, so its role should be understood as one component within a broader retention and information governance framework.

Who it's relevant to

Records and information governance managers
Those responsible for designing and overseeing retention policies need to understand the Preservation Hold Library as the point where retention and hold rules are operationally enforced within SharePoint and OneDrive. They should be clear that it preserves copies for disposition control and is distinct from records classification, archival transfer, or the designation of an authoritative record, so that it is positioned correctly within a broader governance framework.
SharePoint and Microsoft 365 administrators
Administrators who configure retention policies, labels, and legal holds should understand that this hidden library is provisioned automatically and stores captured copies of edited or deleted in-scope content. This knowledge helps them anticipate storage consumption, explain why certain content persists after apparent deletion, and troubleshoot situations where items appear inaccessible pending resolution of a retention period or hold.
Compliance and legal hold coordinators
Practitioners managing legal holds within the Microsoft ecosystem rely on the preservation of copies to help ensure that content potentially subject to a hold is not permanently lost through routine user activity. Because legal hold requirements vary by jurisdiction and matter, coordinators should confirm that the applicable configuration aligns with the specific obligations in force rather than assuming universal coverage.
IT support and end-user helpdesk staff
Support staff often field questions about content that cannot be fully deleted or that continues to occupy storage. Understanding that the Preservation Hold Library is expected, policy-driven behavior, and that content may remain there until the relevant retention period or hold is resolved, allows them to set accurate expectations and avoid attempting to circumvent controls that exist for compliance reasons.

Inside PHL

Held content copies
A Preservation Hold Library typically holds copies of content that is subject to a legal hold or retention obligation, capturing versions of items that a user has attempted to modify or delete while the hold is in effect. The precise mechanics depend on the platform and its configuration.
Retained versions and prior states
Where an item under hold is edited, the library often preserves the state of the content as it existed before the change, so that an authoritative version can be produced if required. This supports the integrity and authenticity properties expected of records held for evidentiary purposes.
Association with a preservation or hold policy
Content generally enters the library because it falls within the scope of a defined hold or retention policy rather than through manual filing. The scope of that policy determines what is captured, and this depends on organizational configuration.
System-managed storage separate from active workspaces
The library is typically a system-controlled store distinct from the live locations where users work, intended to keep held content available for disposition review even after users no longer see it in their active environment.
Metadata supporting later identification and disposition
Held items are usually accompanied by metadata that helps identify why an item was retained and when it may become eligible for disposition, which in this context may mean release, further retention, transfer, or destruction depending on policy and jurisdiction.

Common questions

Answers to the questions practitioners most commonly ask about PHL.

Is a preservation hold library the same as an ordinary retention or archive store?
No. Although both retain content, their purposes differ. A preservation hold library exists to preserve records and information subject to a legal hold or similar obligation, protecting them from destruction while the hold is in force. This is distinct from routine retention, which is governed by scheduled retention periods, and from archiving, which typically concerns the ongoing preservation of records of enduring value. Content in a preservation hold library is held because a hold overrides normal disposition, not because its scheduled retention period requires it. The distinction matters because hold-based preservation is generally driven by anticipated or active legal, investigatory, or regulatory needs rather than by the record's routine lifecycle.
Does placing content in a preservation hold library mean the original records are removed from their source systems?
Not necessarily, and this depends on how the mechanism is implemented. In many implementations, a preservation hold library operates by copying or capturing affected content into a protected location while the source items remain in place, so that users can continue to work with the original systems without the hold being circumvented. In other configurations, preservation may be enforced in situ. The key function is to ensure that content subject to a hold cannot be altered or destroyed in a way that compromises its integrity, rather than to physically relocate the authoritative record. Organizations should confirm how their particular system preserves authenticity and integrity, since these properties are what make the held content usable as evidence.
How should a preservation hold library relate to an organization's broader legal hold process?
A preservation hold library is typically one component of a wider legal hold or litigation hold process, not a substitute for it. The library provides a technical means of retaining and protecting affected content, but the surrounding process, such as identifying custodians, issuing hold notices, scoping relevant records, and documenting decisions, remains essential. Because legal hold obligations vary by jurisdiction and sector, organizations often align the library's operation with their governance policies and, where appropriate, legal advice, so that the technical control reflects the actual scope of the obligation.
How can an organization confirm that content in a preservation hold library retains its integrity and authenticity?
Maintaining integrity, authenticity, reliability, and usability is central to the value of held content. Organizations often address this by relying on system controls that prevent alteration or deletion of protected items while the hold is active, and by retaining metadata that records how and when content was captured. Documenting the provenance of held items and the actions taken can support later demonstration that the content has not been improperly changed. The specific mechanisms available depend on the system in use, so organizations should verify what evidence of integrity their implementation can produce.
What happens to content in a preservation hold library when a hold is released?
When a hold is released, the affected content generally returns to normal disposition handling, which may mean it becomes eligible for destruction, transfer, or continued retention according to the applicable retention schedule. Release does not automatically imply destruction; the appropriate outcome depends on organizational policy and any other overlapping obligations. It is often prudent to confirm that no other hold applies to the same content before allowing disposition to proceed, and to document the release decision so the lifecycle of the affected content remains defensible.
How should overlapping or multiple holds affecting the same content be managed?
Where more than one hold applies to the same content, the content should typically remain protected until all applicable holds are released. Managing this often depends on the system's ability to track which holds apply to which items, so that releasing one hold does not inadvertently expose content still subject to another. Because holds may arise from different matters, jurisdictions, or obligations, organizations frequently maintain records of each hold's scope and status to ensure that disposition only occurs once every relevant obligation has ended.

Common misconceptions

The Preservation Hold Library is a records archive or a place for permanent preservation.
It is generally a mechanism to prevent premature loss of content subject to a hold, not an archival preservation system. Retention under a hold is not the same as archiving, and the eventual disposition may include release or destruction rather than permanent keeping. Whether held content also functions as an authoritative record depends on organizational recordkeeping arrangements.
Everything a user deletes ends up in the library indefinitely.
Typically only content within the scope of an applicable hold or retention policy is captured, and items may become eligible for disposition once the hold or retention requirement lapses. What is captured and for how long depends on the configured policy and applicable requirements, which vary by jurisdiction and sector.
The presence of an item in the library confirms it is an authentic, reliable record.
The library helps preserve content so it is not lost, but the properties that make something an authoritative record, such as authenticity, reliability, integrity, and usability, still depend on how the content was created, captured, and managed. A held copy is not automatically equivalent to a declared record.

Best practices

Confirm exactly what your specific platform captures into its preservation hold mechanism and under what conditions, rather than assuming behavior, since implementation details vary by product and configuration.
Align the scope of holds and retention policies with defensible legal, regulatory, and business requirements, recognizing that obligations such as legal holds and statutory retention periods differ across jurisdictions and sectors.
Document why content is being held and which policy or matter it relates to, so that held items can be identified, reviewed, and moved to appropriate disposition when the hold ends.
Distinguish held copies from your authoritative records, and ensure that content requiring long-term or permanent preservation is managed through appropriate recordkeeping or archival processes rather than relying on the hold library.
Establish a review process for releasing content and applying disposition once a hold or retention requirement no longer applies, treating disposition as potentially including release, transfer, or destruction depending on policy.
Periodically verify that holds are being applied and preserved as intended, and involve legal, compliance, and records functions when defining, extending, or lifting holds.