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NAS or external hard drive

A NAS is a small computer that serves files over your network. An external drive plugs into one computer. This page sets out what the sources say about each and the questions that decide between them.

Checked
2026-10-16
Source
backblaze.com
Sentences checked
20

Read on 2026-10-16. The sources describe NAS and external drives separately and do not compare them head to head, so this page puts their descriptions next to each other and leaves the choice to you.

What a NAS is

Backblaze, in its post comparing NAS and cloud storage, says that NAS, or network attached storage, is a file-level storage system designed specifically to provide centralized and shared disk storage for users on a local area network (LAN). It adds that essentially, NAS is a purpose-built computer that operates its own dedicated operating system (OS), and it contains one or more storage devices that are configured to create a single shared volume. It also says that NAS provides access to files using standard network file sharing protocols such as Network File System (NFS) and Server Message Block (SMB). The same post says that NAS systems are generally managed through a web-based utility accessible over the network.

What a NAS needs from you

Backblaze, in its NAS buying guide, says that some NAS systems are sold without drives. It adds that if you buy drives separately from your NAS, you should choose drives rated for NAS systems, because NAS vendors publish lists of supported drive types. It also says that if you buy drives separately, you should match the drive capacities and models for the most predictable performance across the RAID volume. The same post says that a basic NAS typically includes a Gigabit Ethernet connection (1GigE), which provides a throughput of 1 Gb/s, equivalent to 125 MB/s from your storage system. It adds that this bandwidth is usually sufficient for serving a few users.

The RAID guide explains the volume the quote refers to.

What an external drive does in a backup

Backblaze, in its post “The 3-2-1 Backup Strategy of Data Protection”, says that the 3-2-1 backup rule advises that you keep three copies of your data on two different media with one copy off-site. It adds that if you use a cloud backup service, you only need to worry about keeping your data on two devices, not two separate kinds of media. It also says that if you back up your home computer to an external hard drive and back both of those devices up to the cloud, you have achieved a 3-2-1 backup. The same post says that an on-site backup is a simple way to access your data quickly should anything happen to your computer. It adds that most external hard drives even come with software to ensure they're readily updated.

Backblaze, in its post “SSD 101: How Reliable are SSDs?”, says that an external drive stuffed into a closet for a couple of years is never a good thing, and it doesn't matter whether it is an SSD or HDD inside. It adds that it is better to use an external drive as a backup of your computer as part of your backup plan, just don't make it your only backup.

Backblaze, in its NVMe and M.2 post, says that external SSD drives should not be disconnected from your computer and stored away for long periods of time, and that anything over a year is too long.

What neither one covers

Backblaze, in its NAS vs. cloud post, says that data stored on a NAS is susceptible to various threats, including hardware failures, natural disasters, theft, and cyber attacks such as ransomware. It adds that while RAID configurations offer some level of data redundancy, they do not protect against all forms of data loss.

Backblaze, in its NAS buying guide, says that a NAS gives you fast local access, full data control, and a lower long-term cost of ownership compared to cloud subscriptions, but it doesn't protect you from fire, theft, or ransomware.

Questions to answer first

  • How many people or devices need the same files at once? A drive plugged into one computer serves one computer at a time; a NAS sits on the network.
  • Should the files stay available while one drive is being replaced? That needs more than one drive in the box; see the RAID guide.
  • How much space, now and later? Use the storage calculator before you look at bays or models.
  • Where is the second and third copy? Whichever you pick, write down where the off-site copy lives.

Sources

Checked on 2026-10-16 against Backblaze: NAS vs. Cloud Storage, Backblaze: NAS Buying Guide, Backblaze: The 3-2-1 Backup Strategy, Backblaze: How Reliable are SSDs?, Backblaze: SSD vs. NVMe vs. M.2. Read the source again before you rely on a number, because posts get updated and drive models change.