Explain like I'm five · Cloud

What are DAS / NAS / SAN?

DAS, NAS, and SAN storage, told as the difference between my own desk drawer, the building's shared file room, and its dedicated storage network.

my officethe filing cabinet is full — where do I put more?each desk's own drawer runs out of room fast

Each desk's own drawer runs out of room fast.The office needs somewhere besides the drawers to keep more papers.

same doc, copiedsame doc, copiedsame doc, copiedstore papers separately in each office, and copies pile up that nobody can easily share

Store papers separately in each office, and copies pile up that nobody can easily share.The offices need a way to share one set of papers.

DAS: my own desk drawerNAS: the building's shared file roomSAN: the building's dedicated storage networkDAS=my drawer, NAS=shared file room, SAN=dedicated storage networkDAS, NAS, and SAN differ in how they connect and how widely they're shared

DAS=my drawer, NAS=shared file room, SAN=dedicated storage network.DAS, NAS, and SAN differ in how they connect and how widely they're shared.

DAS plugs directly into my own deskmine alone to use
NAS shares over the hallway (regular) networkfile-by-file, across offices
SAN uses a dedicated network, block-levelfaster than NAS, but pricier
Wider sharing means more connections and permissions to set upand equipment cost climbs with it
DAS vs NAS vs SANDAS: plugs directly into my desk, mine aloneNAS: connects over the hallway (regular) network, shared file-by-fileSAN: a dedicated building network, block-level — faster and pricier than NASthe wider the sharing, the more connections and permissions to set up

Connection method and sharing scope split DAS, NAS, and SAN apart.Wider sharing raises equipment cost. Speed is usually lowest on NAS, which runs over a regular network.

a small office does fine with just a desk drawer (DAS)a dedicated storage network (SAN) is complex and costly to run

A dedicated storage network (SAN) is overkill for a small office.Picking the storage that fits the office's size matters.

In one breath

DAS is a drawer plugged directly into my own desk (just for me). NAS is the building's shared file room, reached over the hallway network (shared file-by-file). SAN is the building's dedicated storage network (block-level, fast, and pricey).

DAS (Direct Attached Storage) connects straight to one server. NAS (Network Attached Storage) connects over a regular network and shares files across multiple servers. SAN (Storage Area Network) uses a dedicated high-speed network for block-level access. Build cost generally rises in the order DAS < NAS < SAN, DAS has the narrowest sharing scope, and NAS, on a regular network, is usually the slowest.

When grown-ups say it

DAS (Direct Attached Storage)
A drawer plugged directly into my own desk. Mine alone to use.
NAS (Network Attached Storage)
The building's shared file room, over the hallway network. Shared file-by-file across offices.
SAN (Storage Area Network)
The building's dedicated high-speed storage network. Block-level — faster than NAS, but pricier.
Block storage
Storage carved into brick-like chunks. Covered in more depth on another page. → block, file, object
File storage
Storage organized like a folder tree. The style NAS uses.
Network bandwidth
How much data the network can carry at once. Directly affects NAS and SAN speed.
Cloud storage
The building itself storing things for you. Any of DAS, NAS, or SAN can sit underneath it.
Backup
Keeping one more copy of the file room elsewhere. The more offices share the data, the more damage its loss causes, so backup matters more.
Next story
The Annex Built Just for the GPUs →
Want another term as a picture book? Request →