NAS vs DAS: which disk array do you need?
A disk array is simply several drives in one box working together. Whether that box should be a NAS or a DAS comes down to one question: does more than one device need the storage?
NAS: storage on the network
A NAS (network-attached storage) is a small, always-on computer with drive bays. It plugs into your router, so every phone, laptop and TV in the house can reach it. It runs its own operating system — Synology DSM, UGREEN UGOS, QNAP QTS — with apps for automatic phone and PC backups, Plex or Jellyfin media streaming, Docker and remote access. The price of that convenience is the box itself: compare models by price per bay, from 2-bay home units to 4-bay and larger.
DAS: storage for one computer
A DAS (direct-attached storage) enclosure connects to one computer over USB or Thunderbolt, like a big external drive. There is no operating system to manage and nothing on the network, and over Thunderbolt or 10Gbps USB it can be faster than a NAS on ordinary gigabit Ethernet. It suits video editing, a single editing workstation's archive, or a backup target for one machine.
RAID, JBOD and what “array” really means
- RAID 1 (mirror): two drives with identical copies. Half the raw space, survives one failure.
- RAID 5: three or more drives; one drive's worth of space holds parity. Survives one failure.
- RAID 6: four or more drives; two drives' worth of parity. Survives two failures — sensible with very large drives.
- JBOD: each drive appears separately, no redundancy. Many DAS boxes offer this, and some NAS systems build their own redundancy on top.
RAID keeps you running when a drive dies; it is not a backup. Deleting a file deletes it on every drive in the array.
Which drives go in?
Both kinds of box want CMR drives designed for multi-drive enclosures — Seagate IronWolf, WD Red Plus/Pro, Toshiba N300, or enterprise drives at larger sizes. Our NAS drive hub ranks them by price per terabyte and works out what it costs to fill a 2-, 4-, 5- or 8-bay array. For a single spare drive, a docking station or enclosure is far cheaper than either.
Quick answer
- Shared family storage, phone backups, Plex: a 2- or 4-bay NAS.
- Fast bulk storage on one desktop or Mac: a DAS over USB 10Gbps or Thunderbolt.
- Occasional backups to a spare drive: a dock or a single enclosure.