Your files can live in four places: inside your computer, on a drive attached to it, on a device on your home network, or on someone else's servers. Each has a distinct set of strengths, and most confusion about storage comes from using one for a job another does better.
The four options at a glance
| Speed | Cost per TB | Capacity | Access from | Survives fire? | |
|---|---|---|---|---|---|
| Internal | Fastest | Highest | Limited | One device | No |
| External | Fast | Low | Large | One device at a time | No |
| Network (NAS) | Medium | Low-medium | Very large | All devices at home | No |
| Cloud | Slowest | Subscription | Unlimited-ish | Anywhere | Yes |
The last column is the one that matters most and is thought about least. Only one of these is off-site.
Internal storage
The drive inside your computer or phone.
Good at: speed. It's directly connected and dramatically faster than anything else, which matters for the operating system, applications, and files you're actively working on.
Bad at: capacity and cost. Internal storage is the most expensive per terabyte, and on modern laptops it's frequently soldered in and can't be upgraded. Choosing too little at purchase is a decision you live with for the life of the machine.
What belongs here: the operating system, applications, current projects, and anything you use daily. That's it.
Rule of thumb: keep 10–15% free. Below that, systems slow down and misbehave.
Buying advice: when configuring a new machine, more internal storage is usually worth the premium precisely because you can't add it later. But if the price jump is steep, an external drive plus cloud on-demand sync covers the gap perfectly well.
External storage
A drive that plugs into your computer.
Good at: cheap capacity. This is the lowest cost per terabyte of any option, by a wide margin, and it's a one-time purchase with no subscription.
Bad at: availability. It's connected to one machine, and only when you've plugged it in. Nothing else in the house can reach it.
What belongs here: backups, archives, finished projects, large media libraries, anything you access occasionally rather than daily.
The critical caveat: an external drive is one device. If your only copy of something is on it, you have one copy. Every archive on an external drive needs a second copy somewhere.
Types: spinning drives are cheaper and higher capacity; SSDs are faster, smaller, and more shock-resistant. For backup and archive, spinning drives are usually the better value.
Network storage (NAS)
A small box on your home network with drives inside it, reachable by every device in the house.
Good at: shared access. Everyone's laptop, phone, tablet, and TV can reach the same files without anything being plugged in. It can also hold multiple drives with redundancy, so a single drive failure doesn't lose data.
Bad at: cost and complexity. It's a real up-front purchase — the box plus drives — and it's a computer that you now maintain: updates, drive replacements, configuration. It's also slower than a directly-attached drive, limited by your network.
What belongs here: shared household media, a central photo archive, backups from multiple computers, anything more than one person needs.
The redundancy misunderstanding: a NAS with mirrored drives protects against a drive failing. It does not protect against fire, theft, deletion, or ransomware, because it's one device in one building that your computers can write to. A NAS is not a backup. It's convenient storage that needs its own backup.
Worth it when: you have several devices, more than one person, and enough data that cloud subscriptions are getting expensive. Not worth it for one person with a laptop.
Cloud storage
Files on a provider's servers, reachable from anywhere.
Good at: access and location. Available on every device, everywhere, and — uniquely among these four — it's off-site. A house fire doesn't touch it.
Bad at: ongoing cost and dependence. You're paying forever, and you're dependent on a company, an account, and an internet connection.
What belongs here: documents, anything you need on multiple devices, anything shared with other people, and a copy of your irreplaceable material.
The critical caveat: cloud sync is not backup. Deletions propagate. It handles hardware disaster brilliantly and mistakes not at all.
Deciding what goes where
Ask three questions of any collection of files:
1. Do I use it daily? Yes → internal. No → somewhere else.
2. Does more than one device or person need it? Yes → network or cloud. No → external is fine.
3. Would losing it be a disaster? Yes → it needs to exist in at least three places, one of them off-site.
Most people's answers produce the same shape: current work on the internal drive and in the cloud, archives on external drives, and the irreplaceable core in all of them.
Three worked setups
The single laptop, minimal budget
- Internal: operating system, applications, current work
- Cloud: documents and photos, on-demand mode so they don't consume local space
- External drive: automated backup, unplugged between weekly runs
- Second external drive: the irreplaceable core, stored at a relative's house
Total hardware cost: two drives. Covers everything, including off-site.
The household with several devices
- Internal on each machine: system and current work
- NAS: shared media, family photo archive, backups from every computer
- Cloud: documents and the irreplaceable core, off-site
- External drive: a backup of the NAS, rotated off-site
The NAS is the convenience layer. The cloud and the rotated drive are the protection layer. Skipping either leaves the NAS as a single point of failure.
The small business
- Internal: current work
- Cloud storage: all working files, synced across the team
- NAS or server: local shared storage and fast local backup
- Cloud backup service: off-site, with retention
- External drive: monthly archive, stored off-site
The addition is retention — businesses need to recover from mistakes discovered months later, which requires backup with long history rather than just a current copy.
The two mistakes to avoid
Mistake one: treating one copy as safe. Any single location — however expensive, however redundant — is one copy. NAS redundancy protects against drive failure and nothing else. Cloud protects against fire and not against deletion. Neither is a complete answer alone.
Mistake two: using the expensive tier for cold data. Paying for premium cloud storage to hold a decade of finished projects, or filling an internal drive with archives, is spending the most per terabyte on the data that needs it least. Archives belong on cheap external drives, duplicated.
What to buy first
If you currently have only internal storage:
- An external drive — cheapest, biggest immediate improvement, enables backup
- Cloud storage for documents and off-site protection
- A second external drive for the off-site copy
- A NAS, only if you have multiple devices and people and enough data to justify it
Most households never need step four. Most households genuinely need steps one through three, and stopping at step one is where the majority of people are.
Next in this series: How to Keep Files in Sync Across Phone, Tablet, and Laptop