How to recover data from Thecus N4520 NAS

Is your network drive gone, and you are wondering what to do? Has a RAID system crashed, and your files are no longer accessible? Does your device display an error while booting? Have you accidentally rebuilt your RAID system? Are several hard disks out of order?

How to recover data from NAS Thecus N4520

Thecus N4520 NAS Data Recovery in 2024

In this step-by-step tutorial, we’ll show you how to rebuild your RAID and recover data from N4520.

How to recover data from NAS Thecus N4520

Recover data from damaged RAID arrays inaccessible from a computer.

Why can’t ordinary software tools restore files from RAID?

Conventional hard disks keep user’s data by writing it to their surface in a consecutive way, and this is how an entire file is stored on a single hard disk. However, when data is written to a RAID system, a file is divided into several parts. Then these parts are written consecutively to all hard disks within such array. The size of such parts may range from 2 KB to 2 MB, so each file is stored on several hard disks at the same time.

Such approach helps to speed up read and write operations, and it is evident that saving two parts of a file having the size of 1 GB to two hard disks simultaneously is much faster than saving the same 1 GB of data to one hard disk. However, this peculiarity makes file recovery more complicated.

Various RAID levels store information in different ways. Additionally, manufacturers like Thecus also introduce some modifications to this process, and that is why data can be written to hard disk in a wide variety of ways.

Are there any specific system logs or event notifications to monitor for early detection of data loss on NAS Thecus N4520 devices?

Yes, Thecus N4520 devices have several system logs and event notifications that can be monitored for early detection of data loss. Here are some specific logs and notifications to monitor:

  1. System Logs: The NAS device maintains system logs that record various events and activities. These logs can provide valuable information about any errors or issues that may lead to data loss. Monitor the system logs regularly for any unusual or critical entries.
  2. RAID Status Notifications: The Thecus N4520 supports RAID configurations for data protection. It is essential to monitor the RAID status notifications to ensure the integrity of the RAID array. Any notifications indicating a degraded or failed RAID status should be investigated promptly to prevent data loss.
  3. Disk Health Notifications: The NAS device can monitor the health of individual hard drives. It can generate notifications if any disk shows signs of failure or is experiencing errors. Monitoring these notifications can help detect disk failures early, allowing for timely replacement and data recovery.
  4. SMART Monitoring: The Thecus N4520 supports SMART (Self-Monitoring, Analysis, and Reporting Technology) for hard drives. SMART attributes provide detailed information about the health and performance of the drives. Regularly monitor the SMART attributes and look for any indications of potential drive failures.
  5. File System Check Notifications: The NAS device performs periodic file system checks to ensure the integrity of the stored data. Monitor the notifications related to file system checks to identify any inconsistencies or errors that may lead to data loss.
  6. Backup Job Notifications: If you have configured backup jobs on the NAS device, monitor the notifications related to backup job status. Any failures or errors in the backup process can indicate potential data loss if not addressed promptly.

It is recommended to enable email notifications for these events and logs so that you can receive alerts in real-time. Additionally, regularly reviewing the NAS device's management interface or using dedicated monitoring software can help ensure early detection of data loss.

How to take hard disks out of the NAS and connect them to a PC?

Although NAS N4520 can be accessed over the network, you still need to take the hard disks out of the storage device and connect them to a Windows computer. Only in this case will the software be able to scan them properly. Here is what you should do:

  1. Turn off the storage and disconnect it from the power supply.

    WARNING! Before you start taking hard disks out of your NAS device, read the manual carefully. Incorrect actions may damage your network-attached storage and/or the hard disks within the RAID system.

  2. Take the hard disks out of the NAS one by one, carefully removing them from their slots. Remember that the disks are extremely vulnerable: hitting or dropping them may result in serious physical damage.

  3. Make sure to mark each hard disk in accordance with how they were installed inside the NAS.

  4. Remove the hard disks and connect them to the computer. In this video, we have explored what ports are used to connect hard disks, and what to do if there are not enough ports or connectors.

    Go to view
    How to Order Remote Data Recovery

    How to Order Remote Data Recovery

Restoring data with Hetman RAID Recovery

Hetman Raid Recovery

This program recovers data from damaged RAID arrays and is fully compatible with Thecus N4520. The hard disks that make up the RAID contain technical information about the algorithm used to save files. When launched, Hetman RAID Recovery reads this information and puts the damaged array together. Then you can open the disk and save your files. Also, you can recover the files accidentally deleted from the network drive.

Go to view
How to recover data from a Thecus

How to recover data from a Thecus

N4520 has 4 HDD slots, and it supports the following array types:

  • RAID 0;
  • RAID 1;
  • RAID 5;
  • RAID 6;
  • RAID 10;
  • JBOD;

NAS supports:

  • EXT3;
  • EXT4;
  • XFS;

Safe recovery from disk images

This utility lets you save an entire copy of the disk to file and then work with this image instead of the actual disk. Such feature helps to protect data on the disk from:

  • Overwriting during the recovery process;
  • Loss resulting from bad sectors;
  • User mistakes.

To create an image, do the following:

  1. Make sure that you have enough free space to save the image. The image file size usually equals the disk size.

  2. Select the disk in the main window, and choose from the menu ToolsSave Disk. You can select multiple disks to be saved.

  3. When the image creation wizard starts, you can choose to save the entire disk or select only a part of it. Specify the parameters and click Next.

    Hetman Raid Recovery: Image Creation Wizard
  4. At this stage, you need to choose a directory where to save the image. Choose any disk connected to this PC, or save the image by FTP.

    Hetman Raid Recovery: hoose any disk connected to this PC, or save the image by FTP

Where are user’s files stored?

The Thecus N4520 network-attached storage keeps OS Linux operating system files on a separate RAID 1 (mirrored) array. Usually, all NAS systems create several volumes on every hard disk, and the first of them takes up to 2 Gb of space. This is where operating system files are stored. Other volumes are united into a RAID array where user’s data is written.

Comparison of software for RAID recovery

Product Operating system License type RAID controller support Supported file systems Virtual RAID controller support Data recovery from damaged RAID File preview
Hetman RAID Recovery Windows Paid Yes, over 100 controllers FAT, NTFS, Ext2/3/4, HFS+ Yes Yes Yes
DiskInternals RAID Recovery Windows Paid Yes, over 100 controllers FAT, NTFS, Ext2/3/4, HFS+ No Yes Yes
R-Studio Windows, Mac, Linux Paid Yes, over 200 controllers FAT, NTFS, Ext2/3/4, HFS+ Yes Yes Yes
UFS Explorer RAID Recovery Windows, Mac, Linux Paid Yes, over 1,000 controllers FAT, NTFS, Ext2/3/4, HFS+ Yes Yes Yes
EaseUS Data Recovery Windows Paid Yes, over 20 controllers FAT, NTFS, Ext2/3/4, HFS+ No Yes Yes
ReclaiMe Free RAID Recovery Windows Free Yes, over 100 controllers FAT, NTFS, Ext2/3/4, HFS+ Yes Yes Yes


We will be happy to answer your questions!

Comments (3)

  • Hetman Software: Data Recovery
    Hetman Software: Data Recovery 9.08.2022 12:31 #
    If you want to ask a question about data recovery, from NAS N4520, feel free to leave a comment!
  • Tommie Horler
    Tommie Horler 13.09.2023 20:44 #
    Is it possible to recover data from a NAS Thecus N4520 device if the device is experiencing frequent disconnections or network errors?
    • Hetman Software
      Hetman Software 13.09.2023 22:00 #

      Yes, it is possible to recover data from a NAS device like Thecus N4520 even if it is experiencing frequent disconnections or network errors. Here are a few steps you can take to recover the data:

      1. Check the network connections: Make sure the network cables are securely connected and there are no loose connections. Try using different network cables or ports to rule out any issues with the network connection.
      2. Restart the NAS device: Sometimes, a simple restart can resolve network errors or disconnections. Power off the NAS device, wait for a few minutes, and then power it back on. This can help reset the network settings and resolve any temporary issues.
      3. Update firmware: Check if there are any firmware updates available for your Thecus N4520 device. Updating the firmware can often fix bugs or compatibility issues that may be causing network errors.
      4. Access the NAS locally: If you are experiencing frequent network errors, try accessing the NAS device locally through its IP address. Connect your computer directly to the NAS using an Ethernet cable and access the device's web interface. This can help determine if the network errors are specific to the network or the NAS device itself.
      5. Use data recovery software: If the above steps do not resolve the issue, you can use data recovery software to recover the data from the NAS device. Connect the NAS to a computer using an Ethernet cable and run data recovery software like Recuva, EaseUS Data Recovery Wizard, or Stellar Data Recovery. These software tools can scan the NAS device and recover lost or deleted files.
      6. Seek professional help: If you are unable to recover the data using the above methods, it is recommended to seek professional help from a data recovery service. They specialize in recovering data from various storage devices, including NAS devices, and have advanced tools and techniques to recover data even in complex scenarios.

      Remember to always have a backup of your important data to avoid data loss situations.

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Vladimir Artiukh

Author: Vladimir Artiukh, Technical Writer

Vladimir Artiukh is a technical writer for Hetman Software, as well as the voice and face of their English-speaking YouTube channel, Hetman Software: Data Recovery for Windows. He handles tutorials, how-tos, and detailed reviews on how the company’s tools work with all kinds of data storage devices.

Oleg Afonin

Editor: Oleg Afonin, Technical Writer

Oleg Afonin is an expert in mobile forensics, data recovery and computer systems. He often attends large data security conferences, and writes several blogs for such resources as, Elcomsoft and Habr. In addition to his online activities, Oleg’s articles are also published in professional magazines. Also, Oleg Afonin is the co-author of a well-known book, Mobile Forensics - Advanced Investigative Strategies.


Questions and answers

  • What are the necessary steps to connect the NAS Thecus N4520 to a router?

    To connect the NAS Thecus N4520 to a router, you need to follow these steps:

    1. Power on the Thecus N4520 and the router.
    2. Connect one end of an Ethernet cable to the LAN port on the back of the Thecus N4520.
    3. Connect the other end of the Ethernet cable to an available LAN port on the router.
    4. Ensure that both the Thecus N4520 and the router are on the same network. You can do this by checking the IP address settings on both devices.
    5. Once the connection is established, you can access the Thecus N4520's web interface by typing its IP address into a web browser on a computer connected to the same network.
    6. In the web interface, you can configure the settings of the Thecus N4520, including creating shared folders, setting up user access, and configuring network settings.

    Note: It is recommended to consult the user manual or documentation provided by Thecus for detailed instructions specific to your device model.

  • Can the NAS Thecus N4520 be connected wirelessly to a router, or does it require a wired connection?

    The Thecus N4520 NAS requires a wired connection to a router or network switch. It does not have built-in wireless capabilities.

  • Are there any specific router settings or configurations that need to be adjusted in order to successfully connect the NAS Thecus N4520 to the router?

    Yes, there are a few router settings and configurations that you may need to adjust in order to successfully connect the NAS Thecus N4520 to the router. Here are some steps to follow:

    1. Assign a static IP address to the NAS: Log in to your router's administration interface and reserve a specific IP address for the NAS. This ensures that the NAS always gets the same IP address when connected to the router.
    2. Enable port forwarding: If you want to access the NAS remotely over the internet, you'll need to set up port forwarding on your router. This involves forwarding specific ports (such as TCP port 80 for HTTP or TCP port 443 for HTTPS) to the NAS's IP address. Consult your router's manual or support documentation for instructions on how to set up port forwarding.
    3. Disable any firewall or security settings that may block NAS access: Some routers have built-in firewalls or security settings that can block access to the NAS. Make sure to disable any such settings or configure them to allow access to the NAS.
    4. Enable UPnP (Universal Plug and Play): UPnP allows devices on your network to automatically discover and connect to each other. Enabling UPnP on your router can help in automatically configuring the necessary network settings for the NAS.
    5. Check network connectivity: Ensure that the NAS and the router are connected properly with Ethernet cables. Verify that the NAS is getting an IP address from the router and that the network settings on the NAS are correctly configured.
    6. Update router firmware: It's always a good idea to keep your router's firmware up to date. Check the manufacturer's website for any available firmware updates and apply them if necessary.

    These steps should help you successfully connect the Thecus N4520 NAS to your router. However, it's important to consult the user manual or support documentation provided by Thecus for specific instructions related to your NAS model.

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