NAS or External Hard Drive: Which Backup Should You Choose for 300 to 500 GB of Data?

For 300 to 500 GB, a NAS is not automatically necessary

A collection of 300 to 500 GB can contain years of photographs, administrative documents, professional files or records that are essential to a small organisation. Capacity alone, however, is not enough to determine the most suitable backup solution.

An external hard drive may be more than enough to protect a single computer. A NAS becomes more relevant when several computers need to be backed up, several people need access to the same documents or the files must remain permanently available on the network.

In this type of situation, I start by looking at five criteria:

• the number of computers containing important data;
• how often files are created or modified;
• whether several users need to share the same documents;
• whether remote access to the files is genuinely needed;
• whether the user or organisation can monitor backups and alerts.

A real case: protecting around 300 to 400 GB of data

During one job, a client needed to protect around 300 to 400 GB of documents and personal data. We considered several options: a two-bay Synology NAS, two drives designed for NAS use, an external hard drive using Windows File History, and a cloud service such as KDrive for sharing selected documents.

These solutions did not address exactly the same need.

• The external drive provided a straightforward way to back up one computer with limited cost and maintenance.
• The NAS could centralise data and backups from several devices.
• Cloud storage made it easier to share selected documents and added a copy stored away from the home.

The NAS was the most scalable solution, but not necessarily the only sensible one. Before choosing it, I needed to establish whether the client genuinely needed permanently available storage, user accounts, sharing between several computers and remote access.

This case is not a complete comparative test of the products discussed in this article. It simply shows that the same amount of data can be protected in several ways, with very different levels of simplicity, cost and protection.

For a single computer, an external drive is often the most sensible choice

For a private user or self-employed professional whose important data is mainly stored on one computer, I do not automatically recommend buying a NAS. A properly configured external hard drive can provide a simple, affordable and sufficiently reliable backup for this use.

In Windows, File History can automatically save different versions of selected folders. This can help you recover a document that was changed or deleted by mistake, provided the backup drive is available and the backup task is actually working.

WD My Book 8 TB: plenty of capacity, but above all an attractive price

For this article, I selected the 8 TB WD My Book Desktop. An 8 TB capacity is far greater than the initial requirement of 300 to 500 GB. I am not recommending it because that capacity is necessary, but because this version can sometimes cost less than certain 4 TB models.

In this particular case, it makes sense to compare actual prices rather than automatically choosing the capacity closest to your current needs. Eight terabytes leaves considerable room for retaining several versions, backing up other devices or accommodating future growth.

The WD My Book is a mains-powered desktop drive. It is therefore best suited to a fixed installation near the computer or NAS. It is less convenient to carry than a small portable drive, but this matters little when it is used as a backup device at home or in an office.

When is this external drive suitable?

• you mainly need to back up one computer;
• you do not need to keep the files permanently available over the network;
• you want a solution that is easy to replace;
• you want to retain several versions of your files;
• you are prepared to check regularly that backups are completing successfully.

Its limitations

• the drive remains a single physical device that can fail;
• it can be stolen or damaged at the same time as the computer;
• it requires mains power;
• it cannot independently share files over the network;
• if it remains permanently connected, some ransomware may also reach the data stored on it.

The same WD My Book can also be used to back up the contents of a NAS. In that role, it provides a genuinely separate copy from the NAS’s two internal drives, particularly if it is disconnected once the backup has finished.

When a NAS becomes more suitable than an external drive

A NAS is a storage device connected to the network. Unlike a USB drive attached to one computer, it can receive backups from several computers and make selected folders available to different users.

For a self-employed professional, an association, a gîte or a bed and breakfast using several computers, this centralisation can genuinely simplify organisation. Administrative documents, letter templates, photographs and shared files are no longer scattered across several machines.

A NAS is particularly useful when

• several computers need to be backed up;
• several people use the same folders;
• the data must remain available even when a computer is switched off;
• separate accounts and access permissions are required;
• backups need to be centralised;
• remote access is genuinely useful and can be secured correctly.

Synology DS223j: an affordable NAS for straightforward needs

The Synology DS223j is a two-bay desktop NAS. It is a sensible option for a household with several computers, a small association, a self-employed professional or tourist accommodation that wants to centralise documents without moving straight to a more expensive business model.

It can store shared folders, receive backups from several computers and make selected files available on the local network. Synology’s software also makes it easier to manage users and backup tasks, provided the device is configured carefully.

The DS223j is sold without drives. You must therefore add the cost of two NAS-compatible hard drives to the price of the enclosure.

What type of use is the DS223j suitable for?

• back up two or three computers;
• centralise documents and photographs;
• share selected folders between several users;
• set up a relatively straightforward home or association solution;
• keep the enclosure cost within a reasonable budget.

Its limitations

• it is less powerful than a Plus-series model;
• it is not designed to run many demanding applications;
• its network connection is limited to Gigabit Ethernet;
• it still requires updates and regular monitoring;
• it must be backed up to another device;
• it may become limiting if professional use grows considerably.

For backing up just one computer, the DS223j remains more expensive and more complex than an external drive. It makes sense when centralisation and access from several devices provide a real benefit.

Synology DS225+: a more scalable option for a small organisation

The Synology DS225+ addresses a different need. It is still a two-bay NAS, but it is better suited to heavier use, several users or an organisation that wants room to grow.

Its 2.5 GbE network port can speed up some transfers, but only when the rest of the network is compatible. A router, switch or computer limited to Gigabit Ethernet will prevent you from making full use of the faster connection.

For a gîte, bed and breakfast, small business or association regularly using several computers, the extra cost may be justified by better performance and greater scope for future applications.

The DS225+ is better suited when

• several users regularly work with the NAS;
• the amount of data to be backed up is expected to grow;
• network transfers are frequent;
• performance and scalability matter more than the lowest purchase price;
• the NAS is intended for professional or semi-professional use.

When the DS223j remains the more sensible choice

For backing up a few computers, storing photographs and sharing office documents, the DS223j may be entirely sufficient. The DS225+ should not be chosen simply because it is more powerful. Its value depends on the number of users, the frequency of transfers and the expected growth of the installation.

Which drives should you install in the NAS?

The Synology enclosure does not include any drives. To create a RAID 1 volume, you need two hard drives of the same capacity, ideally designed for use in a NAS.

The WD Red Plus and Seagate IronWolf ranges are intended for this type of use. They are designed for prolonged operation in an enclosure containing several drives, with the vibration and workloads associated with network storage.

WD Red Plus 4 TB: the main option considered

A pair of 4 TB WD Red Plus drives is a sensible configuration for the DS223j or DS225+. Starting with around 300 to 500 GB of data, this capacity leaves considerable room for file versions, backups from several computers and future growth.

You need to buy two of the drive shown below to create the RAID 1 setup described in this article.

The WD Red Plus is suitable for documents, photographs and backups. It does not make the NAS silent, and it can fail like any mechanical drive. Its main advantage is that it is intended for prolonged operation in a NAS environment.

Seagate IronWolf 4 TB: a sensible alternative

The 4 TB Seagate IronWolf is a direct alternative to the WD Red Plus. The selected model uses CMR recording technology and is intended for NAS and RAID systems.

I do not automatically consider the WD drive superior to the Seagate. The right choice may depend on the price at the time of purchase, availability, warranty and services associated with the exact model.

Here again, you need to buy two units to install a pair of drives in RAID 1.

Before buying, check the exact model number, recording technology, warranty and stated compatibility with the NAS. Similar product names do not always mean identical specifications.

RAID 1: two drives do not mean two backups

In a two-bay NAS configured as RAID 1, the same data is written to both drives. If one drive fails, the second may allow the system to continue operating while the failed drive is replaced and the volume is rebuilt.

This redundancy mainly protects against the failure of one drive. It does not create two independent backups.

When a file is deleted, changed or encrypted, the same operation may be reproduced on both drives. RAID 1 therefore does not automatically protect against:

• accidental deletion;
• ransomware;
• a synchronisation error;
• file or file-system corruption;
• theft of the NAS;
• fire or water damage;
• an administrative mistake;
• a fault affecting the enclosure or several components.

Network recycle bins, file versioning and snapshots can provide additional protection against some mistakes. They are still stored on the same device and do not cover every scenario.

The NAS must also be backed up

A sensible configuration can use the NAS as the main backup destination and then create a second copy of its contents on an external drive. The 8 TB WD My Book discussed earlier can serve this purpose.

Ideally, this external backup should be disconnected once the copy has completed, or used as part of a rotation between several devices. This reduces its exposure to deletion, ransomware and problems affecting the NAS at the same time.

Another option is to send the most important data to a remote destination or cloud service. It is not always necessary to transfer complete system backups. Administrative documents, irreplaceable photographs and essential professional records can be prioritised.

Cloud storage can complement a backup, but syncing and backing up are not the same

A service such as KDrive can be useful for sharing selected documents and keeping a copy away from the home or business premises. This geographical separation helps protect against theft, fire or water damage affecting the computer, external drive and NAS at the same time.

Cloud storage nevertheless has several constraints:

• the initial upload of 300 to 500 GB can take a very long time on a connection with limited upload speed;
• a full restoration depends on the internet connection;
• the cost is recurring;
• some deletions may be synchronised across all devices;
• versioning and restoration features depend on the chosen service;
• the account should be protected by a unique password and two-factor authentication whenever available.

I therefore always distinguish syncing from backing up. A synchronised folder makes it easier to work across several devices, but a mistake can also spread. Before treating cloud storage as a genuine part of the backup strategy, check version retention, recycle-bin behaviour and the restoration procedure.

APC BX750MI-FR: a UPS that allows the NAS to shut down safely

A NAS often runs continuously. A sudden power cut can interrupt a write operation, an update or a RAID rebuild. A UPS can temporarily maintain power and, when correctly recognised, trigger a safe shutdown of the NAS.

The APC Back-UPS BX750MI-FR has a stated maximum output of 410 W and three French sockets backed by the battery. This should normally be more than sufficient for a two-bay NAS, an internet router and possibly a small network device.

Automatic Voltage Regulation, or AVR, can also correct certain voltage fluctuations without immediately using the battery.

What the UPS actually provides

• temporary power during an outage;
• the ability to shut the NAS down safely;
• protection against some surges and voltage fluctuations;
• temporary operation of the router and local network.

Its limitations

• runtime remains limited;
• the battery will need replacing after several years;
• it does not guarantee absolute protection against lightning;
• it does not replace an independent backup;
• USB recognition and automatic shutdown must be tested after installation;
• the three French sockets may be insufficient if many devices need battery backup.

Do you also need to buy a network switch or Ethernet cables?

Ideally, a NAS should be connected to the router or main network by Ethernet cable. Computers can then access it over Ethernet or Wi-Fi, depending on the required performance and network quality.

For an initial backup of 300 to 500 GB, Ethernet is often preferable. Wi-Fi can work, but the transfer may be slower or less stable, especially when the signal passes through several walls.

You do not automatically need to buy a network switch. It becomes useful only when the router no longer has enough Ethernet ports or several devices need to be connected in the same location.

Three sensible configurations depending on your needs

A simple setup for one computer

• an 8 TB WD My Book or another suitable external drive;
• Windows File History or another automatic backup system;
• regular disconnection of the backup drive;
• a remote copy of the most important documents.

This remains the simplest and least expensive solution. It suits many private users and self-employed professionals who mainly use one computer.

A sensible NAS setup for several devices

• a Synology DS223j;
• two 4 TB WD Red Plus drives or two 4 TB Seagate IronWolf drives;
• an external drive to back up the NAS;
• possibly a cloud copy of irreplaceable folders;
• an APC BX750MI-FR UPS.

This is a sensible configuration for a household with several computers, a small association or a self-employed professional who needs to centralise files.

A more scalable setup for a small organisation

• a Synology DS225+;
• two 4 TB NAS drives, or larger if the expected volume requires it;
• an independent backup on an external drive;
• a remote copy of selected folders;
• a UPS with correctly configured automatic shutdown;
• a suitable Ethernet network if transfers are frequent.

This configuration requires a larger budget and more maintenance. It becomes relevant for a gîte, bed and breakfast, association or small business using several computers and shared documents.

A backup must be tested, whatever hardware you choose

Whether it is stored on an external drive, a NAS or in the cloud, a backup must be checked. A message saying that the task completed does not guarantee that every expected folder is present or that the data can be restored.

I recommend checking regularly:

• the date of the latest successful backup;
• any errors or alerts;
• whether the genuinely important folders are included;
• the remaining free space;
• the condition of the drives;
• whether several files can be restored to a temporary folder;
• the procedure for restoring the data to another computer.

If the files are already inaccessible, the priority is no longer to configure a new backup but to avoid making the situation worse. The available options then depend on the condition of the storage device. I explain this distinction in my article about data recovery and the situations that require a specialist laboratory.

Back up before cloning, reinstalling Windows or replacing a drive

A backup becomes particularly important before replacing a drive, migrating to an SSD or reinstalling Windows. These operations can be carried out safely, but errors, failure of the original drive or selection of the wrong disk can still cause data loss.

When the existing drive is still healthy, it may be possible to transfer the system by cloning it. In other cases, a clean installation is more sensible. I explain the criteria I use when choosing between disk cloning and a clean Windows installation.

If the aim is also to improve the performance of a computer still using a mechanical hard drive, replacement can make a real difference. However, the drive used to run Windows must be distinguished from the device used to back up the data. My guide to upgrading from an HDD to an SSD explains this upgrade.

NAS or external drive: my advice for different situations

For a single computer containing 300 to 500 GB of data, I would generally start with a sufficiently large external drive, automatic backups, regular checks and a second copy of irreplaceable files.

I am more likely to recommend a NAS when several computers need to be backed up, shared folders must remain available or a small organisation needs to centralise its documents.

The Synology DS223j suits straightforward, reasonable requirements. The DS225+ offers more performance and scalability, but its additional cost is justified only when there is a genuine need.

In both cases, WD Red Plus and Seagate IronWolf drives are sensible options for internal storage. RAID 1 improves continuity if one drive fails, but the NAS still needs to be backed up to an external drive or remote destination.

The aim is not to buy as much equipment as possible. It is to build a solution that matches the number of computers, the rate at which data changes, the need for sharing and the ability to monitor backups over time.

Frequently asked questions about NAS devices and external drives

What capacity should you choose to back up 500 GB of data?

A 2 TB device can already provide comfortable headroom for 500 GB of data. A larger capacity may be worthwhile when it is attractively priced, several versions need to be retained or the amount of data is expected to grow considerably.

Why buy an 8 TB drive for only 500 GB of data?

An 8 TB capacity is not necessary for only 500 GB of data. It may nevertheless be worthwhile when the 8 TB drive costs less than a 4 TB model. The decision should then take account of the actual price, warranty and intended use.

Does a two-drive NAS hold two separate backups?

No, not when it is configured as RAID 1. The same data is duplicated across both drives so that the system can tolerate the failure of one of them. A deletion or encryption can also be reproduced on both drives.

Should you leave the external drive connected all the time?

This makes automatic backups easier, but increases exposure to errors, power surges and some ransomware. Disconnecting the drive after the backup or rotating between two devices provides additional protection.

Is cloud storage enough to back up all your data?

It can be an important part of the strategy, particularly because it provides a remote copy. You must nevertheless check upload and restoration times, recurring cost, version retention and the difference between syncing and backing up.

Does a UPS protect a NAS against lightning?

A UPS protects against some outages and voltage fluctuations and, above all, allows the NAS to shut down safely. It does not guarantee absolute protection against lightning or a major surge.

How often should you test a backup?

The frequency depends on the importance of the data and how often it changes. A small organisation producing documents every day should carry out checks more often than a private user who only occasionally adds photographs. At a minimum, perform a test restoration after installation and repeat it regularly.