In short
To choose a NAS, start from the use (files, backups, photos, video surveillance or virtual machines), the space needed now and in a few years, bays for growth, the RAID type for the protection you want, drives compatible with the model, and the network: a fast NAS needs a network to match.
RAID types
| Type | Minimum drives | Tolerates failure of | Usable capacity |
|---|---|---|---|
| RAID 1 | 2 | 1 drive | One drive’s worth |
| RAID 5 | 3 | 1 drive | All but one |
| RAID 6 | 4 | 2 drives | All but two |
| RAID 10 | 4 | 1 drive per pair | Half |
| SHR (Synology) | 2 | 1 drive (SHR-2: 2) | Makes use of mixed drive sizes |
What to look at
- Bays: a few more than you need today, to grow without replacing the unit.
- Drives: from the vendor compatibility list, NAS or surveillance drives depending on use.
- CPU and memory: they matter with many users, virtual machines or surveillance.
- Network: 2.5 or 10 Gb ports if you work with large files.
- SSD cache: speeds up access in some professional uses.
- Protected power with a UPS that shuts the NAS down cleanly.
Remember
No RAID replaces a backup. The NAS needs its own off-site copy, in the cloud or on another NAS.