Synology vs TrueNAS or Unraid: Should You Really Migrate?

Synology

Maybe your Synology NAS still works perfectly well, but you have reached the limits of its hardware. Perhaps you want more control over drive selection, networking, memory, GPUs, containers, or future upgrades. Or maybe recent Synology hardware and compatibility policies have made you reconsider whether DSM is still the storage platform you want to build around.

The safest path to TrueNAS Scale or Unraid is to build the new storage environment separately, copy your data while the Synology remains intact, verify the destination, move services one at a time, and only erase or repurpose the old NAS after you know everything is working.

That requires more temporary storage, but it dramatically reduces the risk of turning a platform change into a data-loss event.

Step 1: Decide What You Are Actually Migrating

Before purchasing hardware, inventory what your Synology NAS currently does.

Your migration list might include:

SMB shared folders
NFS shares
Synology Drive data
User home folders
Photos and media
Docker or Container Manager data
Virtual machines
iSCSI storage
Surveillance recordings
Backup repositories
Application databases
Synology package data
User and group permissions

This step matters because copying files is only one part of leaving DSM.

A 20 TB Synology being used exclusively as an SMB file server is relatively straightforward to migrate. A NAS running Synology Drive, Photos, Container Manager, Hyper Backup, Active Backup for Business, directory services, and multiple applications requires considerably more planning. Synology consulting can help plan complex NAS migrations safely.

Start by separating portable data from Synology-specific services.

Documents, photos, videos, and ordinary shared folders are portable. DSM packages and their configurations may not have direct equivalents on another operating system.

Step 2: Choose TrueNAS or Unraid Based on the Destination You Want

This article is not about declaring TrueNAS or Unraid universally better than Synology. They solve the migration problem differently.

TrueNAS is attractive when ZFS, storage integrity, snapshots, replication, structured datasets, and more traditional storage-server architecture are priorities. Current TrueNAS uses ZFS pools composed of physical disks and vdevs.

Unraid is particularly attractive when hardware flexibility, mixed-capacity drives, applications, containers, media workloads, and gradual storage expansion are important. Its traditional array architecture stores data on individual disks while optional parity provides protection.

Your choice affects how you should buy and organize the new drives, so make it before transferring anything.

Step 3: Don’t Pull Your Synology Drives and Put Them Straight Into TrueNAS

This is one of the most important migration mistakes to avoid.

TrueNAS can import an existing storage pool when those disks already contain a compatible ZFS pool. Its current documentation explicitly states that its pool-import procedure applies to disks containing ZFS storage pools.

A normal Synology SHR, RAID, or Btrfs storage configuration is not automatically a TrueNAS ZFS pool.

Therefore, do not plan your migration around:

Turn off Synology → remove drives → insert into TrueNAS → import everything.

Instead, create the new ZFS pool on destination storage and transfer your files across the network.

This is one reason migration temporarily requires enough storage to hold both the source and destination datasets.

Step 4: Be Equally Careful When Reusing Drives With Unraid

Unraid offers considerably more per-disk flexibility, but you should still never assume that inserting your existing Synology drives will preserve their contents.

New Unraid array devices can require clearing and formatting depending on the array configuration. Unraid’s documentation explicitly warns administrators to confirm disk serial numbers because formatting erases the disk permanently.

Its documentation also notes that changing the filesystem on an existing drive requires moving the data elsewhere before reformatting.

So the same fundamental migration rule applies:

Do not repurpose a Synology disk until another verified copy of its data exists.

Step 5: Build the Destination Storage First

For TrueNAS, determine your ZFS topology before copying data.

Think about:

Number of disks
Disk capacities
Vdev layout
Redundancy
Future expansion
Dataset structure
Snapshot requirements
SSD/NVMe requirements
Backup strategy

ZFS rewards planning upfront.

With Unraid, determine which disks will become data disks, whether you will use single or dual parity, and whether SSD or NVMe pools will handle applications and frequently accessed data. Unraid requires parity disks to be at least as large as the largest data disk. Do this design work before transferring terabytes of information.

Step 6: Recreate Your Folder and Share Structure

Don’t simply create one giant folder called Synology-Migration.

Use the move as an opportunity to recreate a sensible destination structure.

For example:

Business

Projects

Users

Media

Archive

Backups

On TrueNAS, these logical divisions may become separate ZFS datasets where different snapshot, quota, compression, and permission policies can be applied. On Unraid, you can recreate appropriate shares and determine how data should use the array and pools. Try to preserve familiar share names where possible. Doing so can reduce the number of mapped drives, scripts, applications, and client systems that must be reconfigured later.

Step 7: Plan Permissions Before Copying Everything

Permissions are frequently overlooked during NAS migration.

A folder containing all the correct files is not necessarily a successful migration if users can no longer access those files or suddenly have access to information they should not see.

Document:

Users
Groups
Shared-folder permissions
ACLs
Service accounts
Read-only access
Application accounts

TrueNAS specifically warns that third-party NAS migrations involving ACLs require careful identity planning. Accounts referenced by NFSv4 ACLs and Windows security descriptors need to exist appropriately on the destination. For a small home environment, manually recreating permissions may be easiest. For a business using Active Directory or another centralized identity provider, preserving identities and ACL relationships deserves considerably more attention.

Step 8: Perform the First Bulk Copy While Synology Stays Online

Now transfer the data.

Possible migration methods include:

SMB
Rsync
Robocopy
NFS
Dedicated migration utilities

TrueNAS documents several approaches for migrating from third-party NAS systems, including SMB-based transfers, Robocopy for Windows environments, rsync for appropriate Unix/Linux workflows, and other migration methods depending on the workload.

For large datasets, rsync can be particularly useful because subsequent passes can transfer only changes instead of copying everything again. TrueNAS supports rsync over SSH or module-based connections. The important point is that the Synology remains operational during this initial copy. Users can continue working while the bulk of the data moves.

Step 9: Don’t Trust “Transfer Complete”

Once the first copy finishes, verify it.

At minimum, compare:

Folder counts
File counts
Total logical data size
Important large files
Recently modified files
Permissions
Representative documents
Media files
Application data

For important environments, use checksums or another integrity-verification method rather than relying solely on directory sizes.

Also open files from the new NAS.

Test an Excel workbook.

Play a video.

Open a large PDF.

Access a deeply nested folder.

Test files with unusual names.

Verify user permissions.

A successful copy command is not the same thing as a validated migration.

Step 10: Run a Final Incremental Synchronization

After the bulk transfer is verified, schedule the actual cutover. At that point, stop users or applications from modifying the source data. Then perform one final synchronization from Synology to the destination. Because most of the data has already moved, this pass should only need to transfer files created or modified since the first migration. This approach can significantly reduce downtime compared with shutting down a production NAS before beginning a multi-terabyte copy.

The sequence becomes:

Bulk copy → verify → freeze writes → incremental copy → verify again → cut over.

Step 11: Migrate Applications Separately From Files

Do not assume DSM packages will migrate with their underlying files.

For example, leaving Synology may require you to replace or redesign services provided by:

Synology Drive
Synology Photos
Hyper Backup
Active Backup for Business
Container Manager
Surveillance Station
Virtual Machine Manager

The underlying photos, documents, container volumes, or VM files may be portable, but the Synology application itself generally is not something you simply install on TrueNAS or Unraid. Plan replacements individually.

For containers, record compose files, environment variables, volume mappings, network settings, secrets, ports, and persistent application data before shutting down the Synology instance. This is where a migration can become more complex than the raw number of terabytes suggests.

Step 12: Repoint Clients Without Immediately Erasing Synology

Once the destination is ready, update clients and services.

That may include:

Windows mapped drives
macOS shares
NFS mounts
Backup jobs
Media applications
Docker containers
Scripts
Cameras
Hypervisors
User shortcuts

If possible, leave the old Synology available temporarily in a read-only or otherwise controlled state. That creates a fallback period. If somebody discovers three days later that an obscure project folder never migrated correctly, the original data is still available.

Step 13: Test the New System Before Calling the Migration Finished

Operate the destination normally before dismantling the old NAS.

Test:

SMB/NFS access
User permissions
Application access
Network throughput
Snapshots
SMART monitoring
Notifications
UPS shutdown
Container workloads
Remote access
Backup jobs
Restore procedures

For Unraid, allow parity initialization or synchronization to complete before assuming the array has its intended protection. Unraid notes that an array can function while parity sync is running but remains unprotected until that process finishes.

For TrueNAS, configure snapshots and your secondary backup strategy rather than assuming ZFS itself eliminates the need for backups.

Step 14: Only Then Repurpose the Synology Drives

Once the new environment has been operating successfully and your data has been verified, you can decide what to do with the old hardware.

Options include:

Keep the Synology as a backup target
Turn it into an off-site NAS
Use it for secondary copies
Retire it
Repurpose its drives
Sell the system after securely erasing it

Keeping the Synology temporarily as a backup target can actually be one of the safest outcomes. You may have moved away from DSM for primary storage without losing the value of perfectly functional hardware.

Most importantly, do not erase the old drives merely because the first transfer finished.

A Safer Synology Migration Has Three Copies During the Risky Part

The ideal migration temporarily looks something like this:

Existing Synology data

↓

Independent backup

↓

New TrueNAS or Unraid storage

During the most disruptive part of the transition, having three copies is far safer than trying to creatively shuffle the same drives between systems.

It may require purchasing destination drives before selling or repurposing the Synology equipment, but that additional cost buys something extremely valuable: a rollback path. If something goes wrong with permissions, applications, the destination filesystem, or the migration itself, your original NAS still exists.

Leaving Synology Doesn’t Have to Mean Starting Over

Policy fatigue, hardware restrictions, expansion requirements, or a desire for more control can all be legitimate reasons to evaluate alternatives to Synology. But dissatisfaction with a platform is not a reason to rush the migration.

TrueNAS and Unraid both provide compelling options for users who want greater control over their storage hardware and software. The safest way to reach either platform is to treat the process as a controlled migration rather than attempting to transform existing Synology disks in place.

Build the destination. Copy the data. Verify it. Perform the final synchronization. Move services. Test recovery. Keep the old NAS intact until you are confident.

About Epis Technology

Epis Technology helps businesses plan storage migrations without turning infrastructure changes into unnecessary data-loss risks. Services include Synology NAS consulting, TrueNAS and alternative storage planning, NAS migrations, large-capacity storage architecture, SMB and NFS migration, virtualization, backup design, ransomware resilience, networking, Microsoft 365 and Google Workspace protection, and disaster recovery. Epis Technology can help inventory an existing Synology environment, design the replacement storage platform, plan data transfer and validation, and maintain reliable backup protection throughout the migration.