The number-one question new Plex server builders ask is "how big should my drives be?" The answer depends entirely on your media habits, quality preferences, and whether you keep everything or rotate content. Here’s how to calculate what you actually need.
Average File Sizes by Quality
These are real-world averages, not theoretical maximums:
- 4K HDR Remux (untouched Blu-ray): 50–80 GB per movie
- 4K HDR (compressed/encode): 15–30 GB per movie
- 1080p Remux: 25–40 GB per movie
- 1080p Encode: 5–15 GB per movie
- 720p Encode: 2–5 GB per movie
- TV episode (1080p): 1–4 GB per episode
- Music (FLAC): 30–50 MB per album
Quick Math
A modest library of 200 movies at 1080p encode (~8 GB average) plus 50 TV seasons (~30 GB each) needs roughly 3.1 TB. The same library in 4K remux would need 14+ TB for movies alone. Quality preference is the single biggest storage driver.
RAID vs Single Drive vs JBOD
Single Drive
Simplest option. A single 16–20 TB drive handles most personal libraries. The risk: one drive failure and everything is gone. Acceptable only if you can re-download or re-rip everything.
RAID (Redundancy)
RAID 1 mirrors two drives (50% usable space, survives one drive failure). RAID 5/6 uses parity across 3+ drives (better space efficiency, survives 1–2 drive failures). ZFS and Unraid offer flexible alternatives with similar protection.
Important: RAID is not a backup. It protects against drive failure, not accidental deletion, ransomware, or controller failure. You still need offsite backups for anything irreplaceable.
JBOD (Just a Bunch of Disks)
Pool multiple drives into one big volume using MergerFS, DrivePool, or similar. No redundancy, but maximum usable space. Works well combined with SnapRAID for periodic parity protection without the overhead of real-time RAID.
NAS vs Direct-Attached Storage
If your Plex server is a dedicated machine, direct-attached storage (internal SATA/NVMe or a USB enclosure) is simplest and fastest. A NAS makes sense when you want shared storage across multiple machines or when the NAS itself runs Plex.
NAS Recommendations for Plex
- Budget (2-bay): Synology DS224+ or QNAP TS-233 — good for small libraries, limited transcoding
- Mid-range (4-bay): Synology DS923+ or QNAP TS-464 — hardware transcoding via Intel CPU, room to grow
- Power user (6–8 bay): Synology DS1621+ or a DIY build with TrueNAS — maximum storage, full GPU support for transcoding
Planning for Growth
Libraries grow faster than people expect. A good rule of thumb: buy 2× the storage you think you need today. Drives are cheap; migrating a full array to bigger drives is time-consuming and risky.
- Start with the largest drives your budget allows (18–20 TB drives offer the best $/TB as of 2026)
- Leave at least one bay empty in a NAS for expansion
- Consider Tdarr to re-encode existing H.264 content to H.265 — typical space savings of 40–60% with no visible quality loss
- Set up automated cleanup for watched content you won’t rewatch (Plex’s auto-empty trash + Sonarr/Radarr retention rules)
SSD vs HDD for Plex
HDDs are fine for media storage. Sequential read performance (which is what streaming is) is nearly identical between HDD and SSD. SSDs help in two specific areas:
- Plex database: Putting the Plex database and metadata on an SSD dramatically speeds up library scans, search, and dashboard loading
- Transcoding temp directory: If you transcode frequently, pointing the temp directory to an SSD reduces I/O bottlenecks during concurrent transcodes
For the media files themselves, stick with high-capacity HDDs. The cost per TB of SSDs doesn’t justify the marginal benefit for streaming workloads.