Mechanical vs Logical Failures in NAS QNAP TR-004U RAID Arrays: Recovery Strategies

Contents

• Why Regular Data Recovery Tools Can’t Restore Files from RAID
• Key Information About the NAS QNAP TR-004U
• 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 QNAP 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 precautions to take while migrating data between NAS QNAP TR-004U devices?

Yes, there are some precautions you should take while migrating data between NAS QNAP TR-004U devices. Here are a few:

1. Backup your data: Before starting the migration process, it is always recommended to create a backup of your data. This will ensure that even if something goes wrong during the migration, you will still have a copy of your important files.
2. Check compatibility: Ensure that both the source and target NAS devices are compatible with each other. Check the specifications and supported models to avoid any compatibility issues.
3. Update firmware: Make sure that both NAS devices are running on the latest firmware version. Updating the firmware can resolve any known issues and improve the overall stability of the devices.
4. Plan the migration process: Create a detailed plan on how you will migrate the data between the devices. This may include steps like creating shared folders, setting up permissions, and transferring the data in an organized manner.
5. Test the migration process: Before migrating all the data, it is a good practice to test the migration process with a small amount of data. This will help you identify any potential issues or errors and allow you to make necessary adjustments before migrating all the data.
6. Monitor the migration progress: Keep an eye on the migration process to ensure that it is running smoothly. Check for any error messages or warnings and take appropriate actions if needed.
7. Verify the migrated data: Once the migration is complete, verify that all the data has been successfully transferred to the new NAS device. Compare the files and folders on both devices to ensure nothing was missed or corrupted during the migration.

By following these precautions, you can minimize the risk of data loss or any other issues during the migration process.

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

Although the NAS TR-004U 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 QNAP TR-004U. 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 QNAP

TR-004U has 4 HDD slots, and it supports the following array types:

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

NAS supports:

• ZFS;
• EXT4;
• EXT3;
• exFAT;
• FAT32 (External Disk Only);
• NTFS (External Disk Only);
• HFS+ (External Disk Read Only);

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 QNAP TR-004U network-attached storage keeps QTS (QuTS hero) 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