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StashRaid

Storage Parameters

Usable Capacity

12 TB

Fault Tolerance

4

Array Resilience

Architecture

RAID 5 • Parity

Fault Tolerance

1 Concurrent Failures Allowed

Current Configuration

RAID 5 (Parity)

12 TB Usable

Total RAW: 16 TB

Disk 01DATA
Disk 02DATA
Disk 03DATA
Disk 04PARITY

Total Drives

4 x 4 TB

Efficiency

75% Utilized

Usable: 12 TBWasted to redundancy: 4 TB

Pros & Cons

  • PRO: Good balance of capacity/speed/safety

  • PRO: Cost-effective redundancy

  • CON: Slower writes due to parity calculation

    This setup prioritizes redundancy but has associated performance or capacity costs.

NAS OS Guide

TrueNAS vs Unraid vs Synology DSM

Choosing the right operating system for your NAS is one of the most important decisions you'll make for your home lab or media server. TrueNAS Scale, Unraid, and Synology DSM each take fundamentally different approaches to storage — from filesystem architecture to drive expansion to app ecosystems. This guide breaks down every major difference so you can pick the platform that fits your hardware, your budget, and your workflow.

Feature Comparison Matrix

A direct head-to-head across ten critical dimensions. Use this as your quick-reference when choosing between the three major NAS platforms.

FeatureTrueNAS ScaleUnraidSynology DSM
File SystemOpenZFS (RAIDZ, Mirror)XFS / Btrfs with Unraid parityBtrfs / ext4 with SHR
Parity / RedundancySingle / double / triple parity (RAIDZ1/2/3)Single or dual parity driveSHR-1 / SHR-2 (hybrid RAID)
Bit-rot ProtectionYes — native ZFS checksums + scrubOptional (Btrfs checksums, not default)Yes — Btrfs checksums on SHR volumes
Drive ExpansionAdd whole vdevs only; no single-drive expansionAdd one drive of any size to the arraySHR: mix drive sizes, expand by swapping or adding
ECC RAM RecommendedStrongly recommended for ZFSNot requiredNot required on consumer units
Minimum Drives2 (mirror) / 3 (RAIDZ1)1 (data) + 1 (parity) min1 (SHR without redundancy) / 2 (SHR-1)
Docker / KubernetesDocker + built-in Kubernetes (TrueCharts)Docker + Compose (community store)Container Manager (Docker + Compose)
PerformanceExcellent — ZFS ARC caching, write-optimizedModerate — single disk writes, no stripingGood — SHR stripes data across drives
PricingFree (TrueNAS Scale, Community Edition)Paid — $59 / $89 / $129 (Lifetime)Hardware bundled — DSM is free with Synology NAS
Hardware CompatibilityBroad (any x86_64, certified list, HBA required)Very broad (any x86_64, USB boot, flexible)Synology hardware only (limited third-party HDDs)

Which NAS OS Should You Choose?

Choose TrueNAS Scale If…

  • You need maximum data integrity (ZFS checksums, snapshots, scrubs)
  • You already have matched drives and can add them in vdev groups
  • You want Kubernetes + Docker for a homelab or production environment
  • You need true enterprise features (Active Directory, iSCSI, NVMe-oF)
  • You are comfortable with a steeper learning curve for maximum control

Choose Unraid If…

  • You have mismatched drives and want to use them all
  • You want easy, one-at-a-time drive expansion
  • You plan to spin down idle drives to save power
  • You want the simplest Docker + app deployment experience
  • You are building a dedicated media server or home NAS

Choose Synology DSM If…

  • You want a polished, turnkey appliance experience
  • You need first-party apps (Photos, Drive, Active Backup, Surveillance Station)
  • Mixing drive sizes with protection (SHR) is a priority
  • You are not interested in building your own hardware
  • You value quiet, low-power, small-form-factor operation

Deep Dive: Key Architectural Differences

Filesystem Philosophy: ZFS vs Parity vs SHR

TrueNAS uses OpenZFS, a copy-on-write filesystem that checksums every data block. This gives you guaranteed data integrity — if a drive develops a bad sector, ZFS detects it during a scrub and repairs it from parity data. Unraid takes a simpler approach: each data drive is a standalone XFS or Btrfs volume, and a dedicated parity drive stores XOR-calculated recovery data. This means reads come from single disks (no striping), and write speeds are limited to the speed of one data disk plus the parity disk. Synology SHR (Synology Hybrid RAID) is a layer on top of Linux mdadm and LVM that splits data and parity into 1 MB chunks distributed across drives. SHR-1 can survive one drive failure; SHR-2 survives two.

Drive Expansion & Flexibility

This is the single biggest differentiator in day-to-day use. With Unraid, you can add a single drive of any size to the array at any time — no rebuild, no rebalancing. Synology SHR is nearly as flexible: you can replace drives one at a time with larger ones and the volume grows automatically, or add additional drives to the SHR pool. TrueNAS ZFS farms are the least flexible: you cannot grow a single vdev. To expand a TrueNAS pool, you must add a whole new vdev (e.g., another 4-drive RAIDZ2). All vdevs in a pool must be identical for balanced performance, or you'll have the odd one bottlenecking writes.

ECC RAM: Do You Really Need It?

A common myth is that ZFS requires ECC RAM. It doesn't — ZFS will happily run on consumer hardware with standard DDR4/DDR5. However, the concern is that ZFS caches data in memory (ARC), and if a cosmic ray flips a bit while the data is in RAM, ZFS will faithfully checksum and store the corrupted data. ECC memory detects and corrects these single-bit errors before they hit disk. For Unraid the stakes are lower because each drive is a self-contained filesystem — a bit-flip corrupts only the data on that drive, not the parity calculation. Synology's higher-end units (DSxxx+ and above) support ECC, but most consumer models do not.

Performance: Caching & Throughput

TrueNAS Scale benefits massively from ZFS ARC (Adaptive Replacement Cache). If you have 32 GB of RAM, ZFS will use a large chunk of it to cache frequently accessed data. This means media files you stream repeatedly come from memory, not disk. Unraid does not have an equivalent read cache — reads always go to the data drive. Synology DSM uses the Linux page cache plus optional SSD caches (read/write). For sequential reads of large media files (4K Blu-rays), all three perform fine. For write-heavy workloads or random I/O (databases, VMs), TrueNAS Scale pulls ahead.

Related Tools & Guides

RAID Capacity Calculator

Calculate usable capacity for RAID 5, 6, 10, ZFS, SHR, and Unraid parity.

ZFS RAID Calculator

Plan ZFS vdev sizes and pool configuration.

SHR Calculator

Calculate usable space with Synology Hybrid RAID.

Build Planner

Plan your NAS or media server build from scratch.

Frequently Asked Questions

Is TrueNAS or Unraid better for a home media server?

Unraid is generally better for home media servers because you can mix drive sizes, add drives one at a time, and spin down idle drives to save power. TrueNAS requires identical vdevs and keeps all drives spinning. If data integrity is critical and you have matched drives, TrueNAS is superior; for flexibility and ease, choose Unraid.

Can I run Docker containers on Synology DSM?

Yes. Synology DSM includes Docker (via the Package Center) and DSM 7.2+ added Container Manager with docker-compose support. However, the ecosystem is less flexible than TrueNAS Scale (native Kubernetes) or Unraid (full Docker Compose with community app store).

Do I need ECC RAM with ZFS on TrueNAS?

ZFS does not require ECC RAM — it runs fine on consumer hardware with non-ECC memory. However, ECC is strongly recommended because ZFS trusts writes held in RAM; a bit-flip in memory could write corrupted data that ZFS will dutifully checksum and store. Unraid does not benefit from ECC the same way, and Synology DSM only supports ECC on their plus/enterprise units.

Can I expand my storage pool without rebuilding on each of these?

Unraid is the easiest — add any size drive to the array. TrueNAS ZFS requires adding an entire vdev (usually 2+ drives for mirror, 3+ for RAIDZ). You cannot expand a single vdev without rebuilding. Synology SHR allows mixing drive sizes within a single volume, similar to Unraid but with two-drive minimum for redundancy.

Which NAS OS has the best app ecosystem?

TrueNAS Scale offers the largest raw ecosystem via Docker + Kubernetes + TrueCharts. Unraid has a strong community app store (Community Applications plugin) with one-click Docker templates. Synology DSM has the most polished first-party apps (Photos, Drive, Active Backup) but a smaller third-party selection. For media servers, all three run Plex, Jellyfin, Sonarr, Radarr, etc.

Ready to Plan Your NAS Build?

Use the StashRaid RAID Calculator to compare usable capacity across TrueNAS ZFS, Unraid parity, and Synology SHR. Enter your drive sizes and see exactly what each OS can offer before you buy a single drive.

Try the RAID Calculator