Decision. Migrate if you want hardware freedom or fear another lock-in cycle; stay on DSM 7.3 if you value the polished bundle and your current box still works. Where to land: TrueNAS SCALE for data integrity (ZFS), Unraid for mixed-disk flexibility and a smooth app store, Proxmox + TrueNAS-VM for full-stack homelabs, UGREEN NASync if you want a turnkey appliance without going DIY [14] [18] [20]. Plan a two-machine, side-by-side transfer — never wipe SHR drives until the new system is verified.
Why people are leaving (even after the reversal)
Synology’s April 2025 policy change required Synology-branded HDDs or HCL-listed third-party drives on every 2025-Plus model; using anything else blocked storage-pool creation and disabled features [2]. After sustained backlash and reportedly poor sales, DSM 7.3 (October 2025) restored third-party 3.5″ HDD and 2.5″ SATA SSD support [1] [4]. M.2 SSDs are still HCL-restricted and Synology has not committed to keeping HDD freedom on 2026 hardware [3].
The reversal calmed the immediate revolt, but for many long-term DSM users it confirmed the trajectory: Synology’s home-consumer focus is described by community veterans as “at an all-time low” [5], and DSM 8 has slipped past its Q4 2025 beta target with no concrete date [35]. If you are reading this, you have already decided the DSM lock-in tax is too high; the rest is execution.
Where to land — OS comparison
| Target OS | Storage model | Strength | Weakness | When to pick | ⭐ Stars |
|---|---|---|---|---|---|
| TrueNAS SCALE (Fangtooth 25.04+) | ZFS, single-drive RAIDZ expansion since OpenZFS 2.3 [12] [13] | Checksums, snapshots, replication, free | Steeper learning curve; demands ECC + ≥16 GB RAM realistically | Data integrity is the priority; you want enterprise-grade FS at home | — |
| Unraid 7 | Mixed-size parity array + optional ZFS pools | Easiest UX; best app store; mixes drive sizes | Paid licence; ZFS as plugin/secondary; weaker integrity story than TrueNAS | You buy one drive at a time, run lots of containers/VMs | — |
| OpenMediaVault 7 | mdadm + ext4/btrfs (DSM-like) | Lightest footprint; runs on a Pi; closest UX to DSM | Smaller plugin ecosystem; manual where DSM was guided | Reusing a low-power box; want the closest “DSM-shaped” replacement | ⭐ 6.6k |
| Proxmox VE + TrueNAS VM | ZFS underneath, hypervisor on top | Run NAS, Docker, VMs, k8s on one box; massive community | More moving parts; you’re running two OSes | You want NAS + virtualisation + containers in one machine [16] [17] | — |
| UGREEN NASync (UGOS Pro) | btrfs/ext4, Synology-style appliance | Turnkey hardware; better CPU than equivalent Synology; Docker support | App library ~25 vs DSM’s 200+; younger product | You want appliance UX without DIY [20] [21] | — |
| TerraMaster / QNAP / Asustor | Vendor OS | Drop-in appliance, no drive lock-in [19] | Different vendor lock-in surfaces (QTS bugs, slower updates) | You are migrating vendors, not philosophy | — |
Trade-off summary: TrueNAS for the file system, Unraid for the experience, OMV for simplicity, Proxmox for headroom [14] [15].
Data migration playbook
1. The core constraint
Synology drives use mdadm + LVM + ext4 (or btrfs) — TrueNAS uses ZFS, Unraid uses its own parity scheme, OMV uses ext4/btrfs over mdadm. You cannot reuse the SHR pool in-place on TrueNAS or Unraid — the disks must be wiped and re-pooled after the data is copied off [7]. You will need either (a) a second machine running side-by-side, or (b) enough scratch storage (USB backup target, cloud, second NAS) to drain the Synology before reformatting.
OMV is the one exception: it can mount your Synology drives mostly as-is because both use the same Linux mdadm + LVM stack [8] [9]. Even there, treat it as read-only data recovery, not “boot OMV on these disks.”
2. Reading SHR on a Linux host (escape hatch)
If the DSM box won’t boot, you can still rescue data. Pull the disks, attach to any Linux machine:
sudo mdadm --assemble --run /dev/md0 /dev/sdb5
sudo vgs # find vg1000 (or similar)
sudo mount /dev/mapper/vg1000-lv /mnt/synology
This works because SHR is just stacked mdadm devices under LVM [8] [9]. Older kernels handle btrfs-on-SHR more reliably than current ones.
3. Transfer paths (DSM still booting)
| Method | Speed | Best for | Notes |
|---|---|---|---|
| SMB mount + rsync (target machine pulls) | Fast on GbE; ~140 MB/s reported on saturated 12-year-old hardware [10] | Most users | Mount Synology share on TrueNAS/Unraid; rsync locally. Preserves metadata. [6] [11] |
| Hyper Backup → rsync target on TrueNAS | Slower; can stall at 100% | Long migration window where DSM keeps running | Configure TrueNAS as rsync destination; DSM keeps backing up until cutover [31] |
| Hyper Backup → S3 (MinIO on TrueNAS) | Fastest for many small files | Encrypted/versioned migration | Avoids ⚠ “transfer encryption” rsync incompatibility; portable backup format |
| External USB intermediate | Limited by USB 3 (~150–250 MB/s) | <8 TB datasets, fewest moving parts | “Just copy the data to a large external USB drive” — cited as simpler than the network dance [10] |
| Cloud (rclone via B2/S3) | Bandwidth-limited | Off-site safety + migration in one | Add ~$6/TB-month transit cost; egress fees apply on read-back |
The canonical command on the target:
rsync -a --info=progress2 /mnt/synology-smb/ /mnt/tank/data/
→ run inside tmux so a dropped SSH session doesn’t kill the transfer [11].
4. Cutover sequence (recommended)
- Stand up the new OS on separate hardware. Don’t touch the Synology drives.
- Initial bulk rsync (days for multi-TB).
- Verify checksums on a sample (
rsync --checksumorrclone check). - Quiesce DSM clients, run a final delta rsync.
- Repoint Time Machine / SMB / backup clients at the new server.
- Run the new server alongside DSM for ≥2 weeks before wiping the old drives — this is your rollback insurance.
- Only then: wipe drives, optionally reuse them in the new pool. ⚠ Synology drives often have older firmware than current Seagate/WD retail — flash before adding to a long-life pool.
Forum migration threads confirm this two-machine pattern as the default; in-place is not recommended [34].
App-by-app replacement matrix
The DSM appeal is the bundle, not any single app. Most replacements run in Docker on whatever new OS you pick — docker compose files turn out to be the dominant migration artifact [32].
| DSM package | Best open-source replacement | Notes | ⭐ Stars |
|---|---|---|---|
| Synology Photos | Immich | Closest UX to Photos; mobile apps, face recognition, on-device ML [22] [23]. ⚠ rapid release cadence — pin versions | ⭐ 99k |
| (alt) | PhotoPrism | Better metadata editing; heavier setup; for power users [24] | ⭐ 40k |
| Synology Drive (sync only) | Seafile | Block-level sync → fastest of the bunch; Drive-replacement only [26] | ⭐ 15k |
| Drive + Calendar + Contacts + Office | Nextcloud | Full Workspace replacement; heavier maintenance [25] | ⭐ 35k |
| Surveillance Station | Frigate | On-device AI detection (Coral / GPU); config is YAML [27] [28]. ⚠ no GUI for camera setup | ⭐ 32k |
| (alt) | Scrypted | HomeKit Secure Video bridge; iOS-first households | ⭐ 5.7k |
| Active Backup for Business (PC/Mac/VM) | Proxmox Backup Server (proxmox-backup ⭐ 204 — official site is the canonical source) | Free; deduplicating; first-class VM support that ABB lacks for non-Hyper-V/VMware [29] [30] | — |
| (alt) | Veeam Community / Restic + rclone | Community Veeam free for ≤10 workloads; Restic for *nix-shaped fleets | — |
| Hyper Backup (NAS→cloud) | rclone + cron, or Borg/Restic to B2/Wasabi | Tiny, fast, encrypted; replication is one bash script | — |
| Container Manager / Docker UI | Portainer CE | Drop-in; what most DSM “apps” already wrap [32] | — |
| Synology Office / Notes / Chat | Nextcloud Office (Collabora), Joplin, Element | No single replacement; pick per family-of-app | — |
| DDNS + Let’s Encrypt + reverse proxy | Caddy or Traefik | Two-line auto-TLS vs DSM’s Control Panel toggles | — |
| Time Machine target | OpenMediaVault SMB share with fruit:time machine = yes, or TrueNAS native TM dataset |
Both options work; TrueNAS exposes it as a checkbox [33] | — |
Pitfalls
- Don’t expect bit-perfect feature parity. Synology Photos’ “shared spaces” model, Surveillance Station’s licensing-included multi-camera workflow, and Hyper Backup’s bundle-everything UX have no single-app replacement — you assemble these out of two or three OSS pieces, sometimes losing minor features.
- Plan for app churn. Immich ships breaking changes monthly; PhotoPrism and Frigate change schemas across majors. The DSM “App Center handles compatibility” guarantee disappears the day you migrate. Pin versions, read changelogs, schedule update windows. [21]
- ECC RAM matters more on ZFS than it did on DSM’s btrfs/ext4. Budget for it on TrueNAS, especially if you skipped it on Synology.
- DSM 8 doesn’t change the calculus. Beta has slipped, rollout is 2026 at earliest, and the underlying drive-policy uncertainty remains [35] [3]. Don’t wait for DSM 8 to make this decision.
- Backups before migration, not during. A second copy of the data on cold storage before you start moving disks turns a bad weekend into a “nothing happened” weekend.
- The home-grade DIY tax is your time. TrueNAS’s average maintenance on a stable home setup is ~1 hour/month; Synology’s was closer to zero. Factor that in honestly.