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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.

Media Server Guide

RAID for Plex & Media Servers

A well-planned RAID setup is the backbone of any serious Plex or Jellyfin media server. But RAID isn't one-size-fits-all — the right choice depends on your library size, your hardware, whether you prioritize flexibility or data integrity, and how tolerant you are of downtime during drive replacements. This guide walks through every consideration so you can build a media storage array that grows with your collection.

Why RAID Matters for Media Servers

Media libraries are uniquely demanding. A single 4K Blu-ray remux with Dolby Atmos can consume 80–100 GB. A collection of 500 films at that quality requires 40–50 TB of storage. RAID lets you pool multiple drives into a single volume with redundancy so that if one drive fails, you don't lose every film on it. Without RAID, a single drive failure means rebuilding and re-ripping — potentially weeks of work.

RAID Is Not a Backup

RAID protects against drive failure only. It does not protect against accidental deletion, ransomware, file corruption, or fire/flood/theft. If you care about your library, maintain a separate backup — even if that means a second NAS or cold storage drives updated periodically. For easily re-rippable media, a parity RAID plus occasional snapshots is often sufficient.

Capacity Planning: How Much Space Do You Need?

Use this table to estimate raw storage requirements before RAID overhead. Actual usable space depends on your RAID level — RAID 5 loses one drive to parity, RAID 6 loses two, Unraid single parity loses one, and ZFS RAIDZ2 loses two.

Media Quality25 Movies100 Movies500 Movies2,000 Movies
1080p (10 GB each)250 GB1 TB5 TB20 TB
1080p Remux (25 GB each)625 GB2.5 TB12.5 TB50 TB
4K SDR (50 GB each)1.25 TB5 TB25 TB100 TB
4K HDR/DV Remux (80 GB each)2 TB8 TB40 TB160 TB
4K Remux + Atmos (100 GB each)2.5 TB10 TB50 TB200 TB

Estimates based on average file sizes for common formats. 4K HDR/DV Remux and Atmos tracks can push individual file sizes to 100 GB+. TV series, extras, and audio tracks add significant additional storage.

RAID Level Recommendations by Library Size

Small Library (Under 10 TB)

Recommended: RAID 5 (3–4 drives) or Unraid single parity (2+ drives).

  • Low overhead — 25% to 33% of total capacity to parity
  • Fast rebuild times with 8–14 TB drives
  • Good read performance for multiple simultaneous streams

Medium Library (10–50 TB)

Recommended: RAID 6 (6+ drives), ZFS RAIDZ2, or Unraid dual parity.

  • Two-drive fault tolerance critical for 16–22 TB drives
  • Rebuild times of 24–48 hours — second failure protection essential
  • ZFS RAIDZ2 adds bit-rot protection via checksum scrubs

Large Library (50–150 TB)

Recommended: ZFS RAIDZ2/RAIDZ3 or Unraid dual parity across multiple arrays.

  • Consider RAIDZ3 if using 20 TB+ drives — rebuild stress on remaining drives
  • Split across multiple pools/vdevs to limit rebuild blast radius
  • Plan for 24–72 hour rebuilds under heavy load

For Reference: RAID 0 (Striping)

Not recommended for any media server with irreplaceable media. RAID 0 offers zero redundancy — any single drive failure destroys your entire array. The performance gain over RAID 5/6 is negligible for sequential media reads.

Transcoding, Direct Play & Storage Considerations

Direct Play vs Transcode: What Your Storage Cares About

Most Plex/Jellyfin users prioritize Direct Play — streaming the original file without transcoding. A single hard drive can handle 10+ concurrent 4K Direct Play streams because the bitrate (~80 Mbps for 4K remux) is well below the sequential read limit of a modern HDD (~200 MB/s). Transcoding adds CPU/GPU load but does not significantly increase disk IO — the bottleneck is the encoder, not the storage. The takeaway: storage performance for Plex is rarely a problem at the RAID level. Focus on capacity and redundancy, not IOPS.

Write Performance During Media Ingestion

The one place RAID performance does matter is when you are adding new media. Automated arr stacks (Sonarr, Radarr, Lidarr, etc.) download, unpack, rename, and move files to your library. This write I/O is amplified by parity calculations in RAID 5/6 and ZFS. Unraid is particularly slow at writes — each file must be read back to calculate parity (or written via a cache pool). If you ingest more than 500 GB/day, consider: (a) a dedicated SSD cache pool (Unraid or Synology), (b) a mirrored ZFS special vdev for metadata, or (c) RAID 10 for write-heavy deployments.

Media Server OS: Unraid vs TrueNAS vs Synology

Unraid

The most popular choice for Plex. Add drives of any size, spin down idle disks, and deploy Plex in Docker with one click via Community Applications. The trade-off is slower write speeds and no built-in checksum-based data integrity.

Compare NAS OS options

TrueNAS Scale

Best-in-class data integrity with ZFS checksums and scrubs. Higher read performance from ARC caching. Requires matched drives in vdevs, which can be expensive to expand. Ideal for curated, irreplaceable collections.

ZFS RAID Calculator

Synology DSM

The polished appliance experience. SHR allows mixing drive sizes with one-click expansion. Plex runs as a native package or Docker container. Limited by the hardware you buy — CPU power for transcoding varies widely by model.

SHR Calculator

Related Tools & Guides

RAID Capacity Calculator

Compare usable capacity across RAID 5, 6, 10, ZFS, SHR, and Unraid parity.

NAS Capacity Guide

Understand usable capacity, overhead, and how RAID levels affect available space.

Build Planner

Plan your Plex server or NAS build from scratch.

Network Bottlenecks Guide

Identify and fix network throughput issues in your media server setup.

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.

Plan Your Media Server Storage

Not sure how many drives you need for your library? Use the StashRaid RAID Capacity Calculator to compare RAID 5, RAID 6, RAID 10, ZFS RAIDZ, Unraid parity, and Synology SHR side by side. Enter your library size, pick your drives, and see the exact usable capacity — including parity overhead — before you buy anything.

Try the RAID Calculator