NAS vs. external hard drives: which is better for backups and shared files? Choose a NAS when several computers or people need the same files over a network, with centralized folders and permissions. Choose an external hard drive when you mainly need a simple, direct-attached backup or a copy that can be unplugged and stored elsewhere. For strong protection, use both: keep working files on the NAS, back up the NAS to an independent external drive, and keep another copy offsite.
Neither device is automatically a complete backup system. A NAS can centralize files and improve availability, but RAID does not replace a separate backup. An external drive is easy to disconnect and carry, but one drive connected to one computer does not provide shared network access or protect against every failure.
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NAS and external hard drives solve different problems
What a NAS does
A network-attached storage (NAS) system is a computer designed to provide storage through your local network. Its disks sit in a dedicated enclosure, while the NAS operating system manages shared folders, accounts, permissions, file services, snapshots or versions where supported, and backup jobs. Computers, phones, media players, and other clients connect through Ethernet or Wi-Fi via the network rather than plugging a storage cable directly into each device.
On Synology systems, DiskStation Manager (DSM) provides shared folders, user and group permissions, and network protocols including SMB, AFP, and NFS. Exact options depend on the NAS model and DSM version. A NAS can therefore act as one organized file location for a household, studio, or small team instead of leaving separate copies on individual computers.
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What an external hard drive does
An external hard drive is a storage disk in a USB enclosure. You attach it directly to a computer, copy files manually, or configure backup software to run on a schedule. You can disconnect it after a job, place it in a drawer or a different building, and reconnect it when you need to restore data or make another copy.
Synology NAS tools can also use an attached USB drive as a backup destination. That makes an external drive useful even when your primary storage is a NAS: it can hold a multi-version backup or a straightforward copy without requiring a second NAS.
Quick decision: which is better for your need?
| Need | Better starting point | Why | Main caveat |
|---|---|---|---|
| Several users or devices need shared files | NAS | Network shares, permissions, and centralized folders let authorized users work from one location. | It requires setup, network access, account management, and ongoing maintenance. Remote access is a separate configuration and security decision. |
| Back up one computer with minimal setup | External hard drive | Direct connection is simple, and scheduled or manual copy workflows are widely supported. | You must manage backup frequency, version history, encryption, and whether the drive remains connected. |
| Keep a copy of NAS data | External USB drive or another independent destination | NAS backup software can write versions or copies to USB and other destinations. | A drive left beside the NAS is still exposed to theft, fire, physical damage, and some malware. |
| Need collaboration and backup protection | NAS plus external and/or offsite backup | The NAS serves active files while another device or location preserves a recoverable copy. | This costs more and requires a defined schedule and a tested restore process. |
Choose a NAS when shared access is the priority
Centralized folders for people and devices
A NAS is the natural choice when the same project files, photos, documents, or media must be available to more than one computer. Instead of passing a USB disk between users, you create a shared folder and let each person connect over the local network. Permissions can limit who may read, edit, or administer that folder.
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1Scan for outdated or missing drivers - takes under a minute2Repair Windows errors before they cause bigger problems3Fix the driver behind crashes, sound loss and screen glitchesFor a small team, separate accounts are safer than one shared password. An administrator can create groups such as staff, family, or contractors, then assign access at the shared-folder level. This gives you a record of which account accessed data and lets you revoke one person’s access without changing everyone else’s credentials.
Network protocols and client compatibility
SMB is the usual choice for Windows, macOS, and many Linux clients. NFS is common for Linux and virtualization workloads. AFP may appear on older systems, but protocol availability and support vary by NAS model and software release. Check the current documentation for your specific unit before planning around a protocol.
Network performance is limited by the slowest relevant link: the NAS port, switch, cabling, Wi-Fi connection, and client hardware. A fast disk cannot make a congested wireless network behave like a wired connection. Treat advertised throughput as model- and workload-specific rather than a guarantee for every file transfer.
Rank #2
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When a NAS adds useful administration
A NAS becomes more valuable as the number of users, devices, and folders grows. Centralized permissions, quotas, user management, scheduled jobs, and monitoring are difficult to maintain when every computer has its own external disk. The trade-off is that someone must administer the NAS: install updates, review alerts, replace failed drives, manage accounts, and verify backups.
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Direct-attached backups
If one computer is the main source of data, a USB drive can be all you need for a local backup. Connect it, select the folders or system image to protect, and schedule a job in your operating system’s backup utility. A direct connection avoids NAS setup, network permissions, and service discovery problems.
For the strongest benefit, disconnect the drive after the backup finishes. A permanently attached disk is convenient, but ransomware, an accidental deletion synchronized to the backup, a power event, or a thief who takes the computer can affect both devices. Use encryption when the drive may leave your home or office.
Portability and offline storage
An external drive is easier to move between locations than a NAS enclosure. You can rotate two drives, keeping one connected for the next backup and the other in a secure place. This rotation creates physical separation without operating a second networked system.
Portability does not make a drive indestructible. Protect it from drops, moisture, heat, and unplanned cable disconnections. Keep a written label or inventory so you know which backup date and encryption key belong to each drive.
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Build the NAS shared-folder setup correctly
- Plan the folders and users first. List the projects or data sets that need sharing. Decide which people need read-only access, which need editing rights, and which account will administer the NAS. Avoid using the administrator account for routine file work.
- Install compatible storage and update the NAS. Confirm the drive type, capacity, and supported configuration for the NAS model. Install the manufacturer’s current stable operating-system update before creating production shares, then record the device name and network address.
- Create shared folders. In DSM, use the shared-folder controls in Control Panel to create a folder for each logical data set. Enable encryption or other protection where your workload and recovery plan support it, and document any keys or passphrases.
- Create users and groups. In the user and group controls, create individual accounts and place them in groups that match their job or household role. Assign the minimum permissions required: read-only where editing is unnecessary, and no access to confidential folders.
- Enable only the file services you need. In the file-services settings, enable SMB, NFS, or another supported protocol according to your clients. Disable unused services and avoid exposing administration interfaces directly to the public internet.
- Connect each client. Map the NAS share using the operating system’s network-drive or file-connection tool. Test creating, editing, and deleting a harmless test file with each account before moving real data.
- Set monitoring and maintenance responsibilities. Turn on storage-health alerts, review disk and system warnings, apply updates during a planned window, and keep an administrator contact and recovery procedure outside the NAS itself.
Use an external drive for a computer backup
- Choose the data scope. Decide whether you need selected folders, a complete system image, application data, or all three. Include browser profiles, mail stores, project files, and any local databases that are not automatically synchronized elsewhere.
- Prepare the disk. Format it with a file system supported by the computers that must read it. Give it a clear name, enable encryption if appropriate, and store the recovery password in a password manager or another protected location.
- Configure a schedule and retention. A daily job may suit active work; less frequently changing archives may need weekly or monthly runs. Keep multiple versions so a damaged or deleted file is not immediately replaced by the same damaged copy.
- Run and inspect the first backup. Confirm that the job finishes without errors, note its duration, and open several files from the destination. A report that says a job started is not proof that the needed data was copied.
- Disconnect or rotate the drive. Safely eject it after the job. If you use two drives, alternate them and keep the idle one in a separate, secure location.
- Test restoration. Restore a sample folder to a temporary location, open the files, and verify that permissions, dates, and versions are usable. Schedule a full recovery exercise at an interval appropriate to the importance of the data.
Back up a NAS to USB storage
Multi-version protection with Hyper Backup
Synology’s Hyper Backup can create multi-version backups of NAS data to an attached USB drive and other destinations. Versions let you retrieve an earlier state after accidental deletion or corruption instead of preserving only the newest copy. Select the shared folders and application data that matter, set a schedule, choose retention rules, and run an initial job while monitoring its log.
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- Set Your Devices Free, Expand Your Digital World: This unified storage hub supports massive capacity up to 64TB.*Storage drives not included. Stop Deleting, Start Storing. You can store 22 million 3MB images, or 2 million 30MB songs, or 43K 1.5GB movies or 67 million 1MB documents! UGREEN NAS is a better way to free up storage across all your devices such as phones, computers, tablets and also does automatic backups across devices regardless of the operating system—Window, iOS, Android or macOS.
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- Blazing Speed, Minimal Power: Equipped with a high-performance processor, 1GbE port, and 4GB RAM on Board, this NAS handles multiple tasks with ease. File transfers reach up to 125MB/s—a 1GB file takes only 8 seconds. Don't let slow clouds hold you back; they often need over 100 seconds for the same task. The difference is clear.
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Synology Knowledge Center explains the benefit this way: “Having a multi-version local copy gives you the advantage of fast recovery in the event of data corruption or accidental file deletion, since the data copy can be retrieved directly from your Synology NAS.” The statement applies to a local copy that actually contains the required versions; it is not a promise that every backup configuration has the same retention.
Direct-copy workflows with USB Copy
USB Copy is a more direct copy workflow with a different feature set. It can suit a simple export or one-way transfer when you do not need Hyper Backup’s version-management approach. Decide whether you need a browsable copy of ordinary files or an application-aware, multi-version backup, then choose the workflow accordingly. Verify the destination contents and the job log after the first run.
Protect the destination
A USB disk connected to the NAS is still a local copy. If the NAS and USB disk share a room, a theft, fire, flood, or destructive malware event can remove both. Eject the drive when practical, rotate multiple destinations, and keep at least one copy elsewhere.
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RAID improves availability, not backup protection
RAID combines multiple disks so a NAS can continue operating after certain disk failures, depending on the RAID level and the condition of the remaining drives. It can reduce downtime and make replacement less disruptive. RAID does not preserve every deleted file, undo ransomware encryption, or protect against theft, fire, a failed controller, or an administrator mistake.
Synology cautions: “However, even when such measure is taken, RAID crash and hard drive failure might still cause data loss.” Treat the array as primary storage or an availability feature, not as an independent backup. A second copy must live on a different device, and ideally in a different place.
Apply the 3-2-1 rule and add an offsite copy
Synology’s 2026 backup guidance recommends the 3-2-1 strategy: keep three copies of important data, on two storage media, with one copy offsite. This is a planning rule of thumb, not a published success rate. For example, active files on a NAS, a versioned USB backup, and an encrypted copy stored at another location satisfy the structure more closely than two disks sitting beside one another.
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- High Speed Data Transmission: The D2-320 hard drive enclosure (a DAS, NOT a NAS) adopts USB 3.2 Gen2 protocol for high-speed data transmission up to 10Gbps. With 2 hard drives in RAID 0, the read/write speed can reach up to 521MB/s (SATA III HDD 8TB x 2). With 2 SSD's in RAID 0, the read speed can reach 1075MB/s (SATA III 1TB SSD x 2)
- Multiple RAID Configurations: The D2-320 is a hardware RAID enclosure and it supports RAID 0, RAID 1, JBOD and SINGLE which can better satisfy various demands of users. In RAID 1, data will be in a mirror backup. When there is a damaged hard drive, you can directly replace the hard drive, and the data will be recovered automatically. This provides an absolute security for the data
- Super-Large Storage Capacity: The D2-320 USB storage enclosure can support up to two 3.5" and 2.5" SATA HDD, as well as 2.5" SATA SSD, with a maximum capacity of 22TB per drive, providing users with up to 44TB (22TB x 2) of storage space
- Intelligent Temperature Control: The D2-320 HDD enclosure has an intelligent temperature-controlled and low-noise fan that automatically adjusts its speed based on the temperature of the hard disk. This feature ensures that the hard disk operates at its best temperature and provides better heat dissipation
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Local backups are excellent for fast recovery, but they do not protect against a fire, natural disaster, or theft that affects all equipment in the same place. Synology’s official backup guidance therefore recommends an offsite copy. The offsite destination may be a rotated drive kept in a secure location or another independent service that you have configured and tested; the important property is physical or administrative separation from the primary equipment.
Compare ownership, not just terabytes
| Factor | NAS implications | External-drive implications | Questions to ask before buying |
|---|---|---|---|
| Usable capacity | Total usable space depends on the number of bays, installed disks, file-system overhead, and any redundancy or reserved space. | Advertised capacity is usually the capacity of one disk, with formatting overhead reducing the available amount. | How much data exists now, how quickly will it grow, and how many historical versions must be retained? |
| Redundancy | Multiple bays can support an array that tolerates some disk failures, subject to the selected RAID level and rebuild condition. | A single drive has no built-in disk redundancy; protection comes from another copy. | Is continued availability during a disk replacement more important than the lowest purchase cost? |
| Access | Many authorized clients can connect over the network at the same time. | Normally one directly connected host uses the disk; sharing requires the host to remain on and configured as a file server. | How many simultaneous users and devices will work with the data? |
| Backup and versioning | NAS software can schedule versions to USB, another NAS, or another destination; features vary by model and software. | Backup software on the computer controls schedules and retention. | Can you see job logs, retain older versions, and restore individual files? |
| Network dependence | File access depends on the NAS, switch or Wi-Fi, and network configuration. | A local backup remains usable when the network is down. | Do you need files during a network outage, or only during scheduled backup windows? |
| Portability | Enclosures are heavier, require power, and are intended to stay installed. | USB drives are easier to rotate and store away from the primary equipment. | Will you regularly move a copy offsite? |
| Noise and power | Fans and disks may run continuously, and power use depends on the enclosure, disks, sleep settings, and workload. | A drive typically draws power only when connected, but exact use depends on the model and host. | Can the location accommodate continuous operation and cooling? |
| Administration | Requires updates, account management, storage-health checks, and backup monitoring. | Requires connection discipline, encryption-key management, and checking backup results. | Who will respond when a job fails or a disk reports an error? |
| Total cost | Includes the enclosure, compatible disks, network equipment, replacement disks, and time spent administering it. | Includes the drive, possible rotation drives, cables, encryption or backup software, and secure storage. | What is the cost of the complete protection plan, not just the first device? |
Common mistakes and how to correct them
“The NAS has RAID, so I am backed up.”
RAID and backup address different failures. Keep an independent, versioned copy and verify that it can be restored.
“The USB disk is connected all the time, so backups are automatic.”
Automation helps only if jobs succeed and older versions remain available. Review logs, test restores, and disconnect or rotate the disk to reduce shared exposure.
“A shared folder means everyone should use one account.”
Shared credentials remove accountability and make it impossible to revoke one person’s access cleanly. Use individual accounts and groups with least-privilege permissions.
“A faster network will fix every slow transfer.”
Check the NAS disks, client storage, protocol, switch, cabling, Wi-Fi signal, and the size and number of files. Small files and many simultaneous users can behave differently from one large sequential copy.
“A local second copy covers disasters.”
If both devices are in the same room, one event can destroy both. Keep an encrypted copy offsite and know how to retrieve it.
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- 【Advanced Home Data & Media Hub】For advanced home users who need phone backup, file storage, and centralized data management. Centralize family photos, 4K videos, movies, computer backups, and personal files in one place while running multiple apps for home entertainment and everyday data management. Suitable for households with growing digital libraries and multiple NAS use cases.
- 【Built for Creators, Media Servers & Advanced Apps】Powered by the Intel N100 Quad-Core CPU, 8GB DDR5 RAM, 2.5GbE networking, and dual M.2 NVMe slots, DXP2800 handles large files and heavier workloads with ease. Run Docker, virtual machines, and media server applications compatible with Plex—ideal for content creators, tech enthusiasts, and advanced home users managing 4K videos, RAW photos, personal media libraries, and multiple NAS apps.
- 【Up to 80TB for Growing Digital Libraries】 Supports up to 80TB of storage using two HDD bays and two M.2 NVMe SSD slots for family photos, movies, RAW photos, 4K videos, work files, and device backups. AI photo management supports recognition of people, objects, scenes, and locations, album organization, and duplicate photo detection. HDDs and SSDs are not included.
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“The first successful job proves the plan works.”
Only a restoration test proves that the backup contains usable data. Restore representative files, permissions, and application data before an emergency occurs.
Practical choices by household or team
One laptop and mostly personal documents
Start with an encrypted external drive and a scheduled, versioned backup. Add a second rotated drive or an offsite copy if losing the laptop and its backup together would be serious. A NAS is optional unless you also need shared media, multiple computers, or centralized access.
Several computers sharing photos and project files
Use a NAS with separate accounts and shared folders, then back it up to USB or another independent destination. Keep an offsite copy for events that affect the whole home or office.
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A small creative or professional team
A NAS can provide a consistent workspace and permissions, but plan capacity growth, network performance, user onboarding, and a person responsible for maintenance. Keep active work separate from the backup destination and test recovery of large projects.
Archive that is rarely accessed
An external drive rotation may be simpler and cheaper to operate than a powered-on NAS. Label each drive with its coverage dates, encrypt it, and maintain at least one copy outside the primary location.
A restore plan is part of the purchase
- List recovery priorities. Identify which files must return first, the acceptable amount of lost work, and the maximum time the business or household can operate without them.
- Document access details. Record NAS administrator recovery steps, backup locations, encryption-key storage, and the software needed to read the backup. Keep this documentation separate from the device.
- Test small restores regularly. Restore a current file, an older version, and a folder with permissions to a temporary location. Open the files and verify their contents.
- Run a full scenario test. Periodically simulate a failed NAS or unavailable computer. Confirm that you can obtain the offsite copy, rebuild the destination, and resume work.
- Update the plan after changes. Adding a user, replacing disks, changing folder names, or switching backup software can invalidate old instructions. Revise the documentation and repeat a test.
Bottom line
For shared files, a NAS is usually better because it provides network access, centralized folders, and managed permissions. For a straightforward backup of one computer or a portable copy, an external hard drive is usually better because it is easy to connect, disconnect, and store separately. The most resilient design combines them: use the NAS for active shared storage, create versioned backups on an independent external drive or destination, and maintain at least one offsite copy under the 3-2-1 approach. Select specific hardware only after measuring your capacity, client network, redundancy needs, maintenance tolerance, and recovery requirements.
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