How to Prevent Data Loss on NAS Thecus N4520 and Recover Deleted Files: Expert Guide

Contents

• Why Regular Data Recovery Tools Can’t Restore Files from RAID
• Key Information About the NAS Thecus N4520
• How to Remove Hard Disks from Your NAS and Connect Them to a PC
  • Step-by-Step Data Recovery with Hetman RAID Recovery
  • How to Safely Recover Data from Disk Images
  • Where Are the User’s Files Actually Stored?
  • RAID Recovery Software: Detailed Comparison

Why Regular Data Recovery Tools Can’t Restore Files from RAID

Conventional hard drives store user data by writing it sequentially across the disk surface, which means an entire file is typically located on a single drive. In contrast, when data is written to a RAID array, each file is split into multiple fragments. These fragments are then distributed and written in sequence across all the drives in the array. Depending on the configuration, fragment sizes can range from 2 KB to 2 MB, so every file is physically stored across several disks at once.

This approach significantly increases read and write performance — after all, writing two halves of a 1 GB file to two drives simultaneously is much faster than writing the full 1 GB to a single disk. However, this same mechanism makes file recovery far more complex.

Different RAID levels use different methods to distribute and protect data. On top of that, manufacturers like Thecus often add their own proprietary structures and variations. As a result, data can be written to disks in many different formats, and each requires a specific approach during recovery.

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 Remove Hard Disks from Your NAS and Connect Them to a PC

Although the NAS N4520 can be accessed over the network, you still need to remove its hard disks and connect them directly to a Windows PC. Only then can the recovery software properly scan and analyze the drives. Follow these steps:

1. Power off the NAS and disconnect it from the power source.

   WARNING! Before removing any drives, carefully read the device manual. Improper actions may damage both the NAS enclosure and the hard disks in the RAID array.

2. Remove the hard disks one by one, gently sliding each drive out of its slot. Remember that hard disks are highly sensitive: any impact or drop can cause serious physical damage.

3. Label each hard disk according to its position inside the NAS. The order of the drives is crucial for correct RAID reconstruction.

4. Connect the drives to your computer. In this video, we explain which ports you can use to connect hard disks and what to do if your PC does not have enough free connectors.

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   How to Order Remote Data Recovery

Step-by-Step Data Recovery with Hetman RAID Recovery

This program restores data from damaged RAID arrays and is fully compatible with Thecus N4520. Each hard disk in the array contains technical metadata describing how files were written. When launched, Hetman RAID Recovery analyzes this metadata, automatically reconstructs the damaged array, and provides access to its contents. After that, you can browse the recovered disk and save your files. The program can also restore files that were accidentally deleted from the network drive.

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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;

How to Safely Recover Data from Disk Images

This utility allows you to create a complete copy of a disk and work with the disk image instead of the physical drive. This approach helps protect your data from:

• Overwriting during the recovery process;
• Additional data loss caused by bad sectors;
• User errors.

To create a disk image, follow these steps:

1. Ensure you have enough free space to store the image. Its size will typically match the size of the original disk.

2. In the main window, select the target disk and choose Tools - Save Disk. You can also select multiple disks if needed.

3. When the Image Creation Wizard opens, select whether you want to save the entire disk or only a specific region. Adjust the settings and click Next.

   

4. Choose the directory where the image will be saved. You may select any available disk connected to your PC or upload the image via FTP.

   

Where Are the User’s Files Actually 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.

RAID Recovery Software: Detailed Comparison