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ONTAP Foreign LUN Import

Learn about the ONTAP data migration program

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The data migration program offers proven solutions to help customers move data from foreign (third party) arrays to ONTAP, and to transition LUNs from NetApp 7 Mode systems to ONTAP—with Foreign LUN Import (FLI) serving as a key component of this migration portfolio. To improve migration success and reduce effort, the program provides the tools, guidance, and enablement needed to execute migrations efficiently and consistently, helping customers adopt NetApp technologies faster and with greater confidence.

Data migrations often come with real operational challenges—extended downtime windows, risk to production workloads, limited resources, and gaps in specialized expertise. As availability expectations continue to rise and downtime becomes less acceptable, migrations must be planned around business continuity. Because performance impact, data integrity, and potential data loss are common concerns in any migration, understanding the core FLI concepts and workflow upfront helps streamline execution and lowers the initial configuration and operational overhead.

FLI is an ONTAP data migration capability that copies user data from a foreign (third party) array LUN into a native ONTAP LUN. ONTAP performs the migration by acting as a SCSI initiator: it reads blocks from the foreign LUN and writes them into the destination ONTAP LUN.

ONTAP FLI was supported when the foreign LUN was reached through Fibre Channel (FC). Beginning with ONTAP 9.19.1, iSCSI FLI support was added to access foreign array LUNs using iSCSI transport on the backend. With iSCSI FLI, the backend path to the source array is iSCSI/TCP, while the front end host access to the ONTAP LUN can be either FC or iSCSI (the backend and frontend can differ).

iSCSI and FC ONTAP FLI support both offline imports (no host I/O during the import) and online imports (host stays connected, with a single short cutover outage).

Key terms

Foreign array

Any storage system that does not run ONTAP (including NetApp 7 Mode in a 7 Mode to ONTAP transition context).

Foreign LUN

A LUN containing user data on the foreign array in that array’s native format.

Import relationship

A persistent pairing between the foreign LUN (source) and ONTAP LUN (destination) used for data copy.

LUN import

The process that transfers the blocks from the foreign LUN into the ONTAP LUN.

High level methodology

Discovery phase

Gather a complete inventory of the environment—hosts, storage systems, and SAN/network fabrics—so you understand what exists and how everything is connected.

Analysis phase

Review the collected inventory and determine the most appropriate migration approach for each host and source array based on compatibility, risk, and operational constraints.

Planning phase

Build and validate the migration plan, provision the destination ONTAP storage, and prepare the required migration and qualification tools and operational runbooks.

Execution phase

Perform the migration (import/copy) and complete the required host remediation and cutover actions according to the selected workflow (online or offline).

Verification phase

Confirm the migrated data and configuration behave as expected, validate host access and multipathing, and document the final state and outcomes for operational handover.

Intended audience

This information is intended for customers, partners, and NetApp field teams who are planning or executing SAN (block/LUN) data migrations to ONTAP, especially migrations that use Foreign LUN Import (FLI) and related migration options.

Primary readers

  • Customer storage administrators / SAN administrators responsible for planning migration approach, preparing ONTAP, coordinating change windows, and validating host access/multipathing.

  • Migration leads / technical project owners who need high-level guidance to choose between FLI, appliance-based options, or host/application-based migration methods, and to estimate timelines and effort.

  • NetApp and partner professional services engineers supporting migration scoping, planning, qualification, and customer enablement (recommended for most but the simplest migrations).

Readers should have basic familiarity with:

  • SAN concepts (LUN masking/mapping, zoning or iSCSI networking, multipathing/ALUA), and standard change-control practices.

  • ONTAP administration fundamentals and the use of supporting planning tools (such as environment data collection and interoperability validation utilities).

Learn about SAN data migration to ONTAP

Migrating SAN data is often constrained by tight downtime windows, production risk, and limited specialist resources. ONTAP Foreign LUN Import (FLI) is a built-in block migration capability that copies data from a foreign (third-party) array LUN to a native ONTAP LUN and supports both offline and online migration styles. While ONTAP does not require a professional-services-led migration, it is still strongly recommended to involve NetApp or qualified partners for scoping, planning, and training—especially for non-trivial environments.

Choosing the right migration approach (high level)

A practical migration strategy may use one primary method and supplement it with other approaches where they fit best. For SAN/LUN-level migrations into ONTAP, FLI is commonly a strong choice; however, some scenarios may be better served by alternatives that are non-disruptive by design.

Common options:
Foreign LUN Import (FLI)

Block/LUN-level migration into ONTAP with online and offline workflows.

Data Transfer Appliance (DTA)

A SAN-attached appliance model that is licensed per TB migrated and supports offline and online migrations.

Host OS or application-based migrations

Useful when the platform provides native mobility or when host or application control is preferred (For example, VMware storage mobility and host-based copy approaches).

Planning migration duration

For initial planning only, a commonly cited benchmark assumption is ~5 hours per host for a host with 8 LUNs totaling ~2 TB, which equates to roughly ~400 GB/hour. This is intentionally a rough planning figure and is unlikely to match every environment. The recommended way to obtain an accurate estimate is to run multiple test migrations of different sizes to measure real throughput in your own storage, network, and host conditions.

Service tools provide a standardized way to collect environment data, validate supportability, and reduce human error during planning and execution.

Active IQ OneCollect

Collects data from storage, hosts, fabrics, and switches for troubleshooting, validation, migration planning, and upgrade assessments.

Interoperability Matrix Tool (IMT)

A web-based utility to confirm supported configurations across NetApp and third-party components.

Solaris Relabeler (when applicable)

Updates VTOC disk labels post-migration so systems reflect updated inquiry information after block-level migrations.

SAN LUN Migrate (sanlunmigrate for FLI projects)

Use a qualification approach to validate foreign array/LUN behavior in the customer environment prior to committing to production migration; this is especially important when transport or vendor behavior differs.