A NAS — network attached storage — is a small always-on box of hard drives that everyone in the house or office can reach over the network. It’s a backup target, a shared drive, a media server and a private cloud in one. This guide explains who actually needs one, how to choose between buying and building, and the rules that keep your data safe once you have it.
Do you need one?
- Yes if several people or devices share large files, or if you have photo and video libraries too big for cloud plans.
- Yes if you want automatic local backups for every machine (including Time Machine for Macs).
- Maybe not if you’re one person with a laptop — an external SSD plus cloud backup is simpler and cheaper.
What people actually use a NAS for
- Backups: every computer backs up automatically over the network.
- Shared project files for a small team, without monthly per-seat cloud fees.
- Photo and video archive with apps that replace phone photo backup.
- Media server (Plex, Jellyfin) for the TV.
- Remote access to your files from anywhere, through the vendor’s app.
- Docker containers for small self-hosted tools.
Buy a ready-made NAS or build one?
| Ready-made (Synology, QNAP, UGREEN, TerraMaster, Asustor) | DIY (TrueNAS, Unraid, a mini PC) | |
|---|---|---|
| Setup | Guided wizard, polished apps | You assemble hardware and configure the OS |
| Apps and support | Vendor app ecosystem and updates | Community and documentation |
| Flexibility | Limited to the vendor’s software | Complete |
| Cost per terabyte | Higher | Usually lower |
| Best for | Anyone who wants it to just work | Tinkerers and home labs |
Important: some vendors restrict which drives are fully supported in newer models. Check the manufacturer’s compatibility list for the exact model you’re buying before you buy drives.
How many bays?
- 2-bay: the common starting point. Two drives mirrored means one can fail without data loss — you get the capacity of one drive.
- 4-bay: better capacity efficiency and room to grow; the usual choice for media libraries.
- Plan capacity for 3–5 years, since adding drives later can mean rebuilding the array.
Choosing drives
- Use NAS-rated drives (WD Red Plus/Pro, Seagate IronWolf) designed for 24/7 operation and vibration.
- Avoid SMR drives for NAS use — they slow down badly during array rebuilds. Manufacturers publish which models are CMR.
- Buy drives in the same capacity, ideally not all from the same production batch.
- An SSD cache is optional and rarely necessary for home use.
RAID is not a backup
This is the single most important thing to understand. RAID protects against a drive failing. It does nothing about accidental deletion, ransomware, fire, theft or a failed NAS. Follow the 3-2-1 rule: three copies of your data, on two different types of media, with one copy offsite. In practice: your computer, the NAS, and a cloud backup (or a second drive kept elsewhere).
Network and placement
- Use Ethernet, never Wi-Fi, for the NAS itself. 2.5GbE is increasingly common and worth having if your router supports it.
- Put it somewhere ventilated — and not on your desk if fan noise bothers you.
- Plug it into a UPS so a power cut doesn’t interrupt a write.
- Weak Wi-Fi elsewhere in the house? See our mesh Wi-Fi guide.
Security basics
- Change the default admin account name and use a strong, unique password.
- Turn on two-factor authentication.
- Keep the NAS operating system and apps updated — NAS devices are a known ransomware target.
- Don’t expose admin interfaces directly to the internet; use the vendor’s relay service or a VPN.
- Enable snapshots if your NAS supports them — they make ransomware recovery far easier.